Thoracic hydatid cysts: an analysis of surgical management in a tertiary care centre in India

Abstract

Introduction and purpose

Though hydatidosis is a ubiquitous zoonosis endemic to India, there is a dearth of literature regarding the management of thoracic hydatid disease (THD) in India. There are no surgical guidelines available. The aim of this study is to analyse the details of THD operated upon in a tertiary care hospital in India and propose a protocol for its management.

Methods

The case files of all adult patients operated upon for THD in our institution between 2009 and 2019 were retrieved and a retrospective study done.

Results

A total of 186 patients, 103 (55.4%) males and 83 (44.6%) females, with a mean age of 34.2 years were studied. The commonest symptom was cough as in 83 (44.6%) patients. Complications were seen in 22 (11.8%) patients. Computerized tomogram (CT) was confirmatory in most patients. Isolated pulmonary disease was seen in 135 (72.6%) patients with 153 (82.3%) uni-lobar involvement. Right lower lobe was most frequently involved as in 56 (30.1%). Extra-pulmonary, intra-thoracic involvement was seen in 6 (3.2%) and synchronous extra-thoracic disease in 45 (24.2%) patients. All patients were initiated on anthelmintics. Postero-lateral thoracotomy was the commonest surgical approach. Twenty (10.7%) patients required lung resections. The mean hospital stay was 5.9 days. Air leak, seen in 10 (5.4%) patients, was the commonest post-operative complication. There was single in-hospital mortality. Age, diabetes mellitus, secondary bacterial infection of the cyst and cyst characteristics were found to significantly affect the surgical outcomes.

Conclusion

Surgery, the treatment of choice for THD, can be done with negligible morbidity and mortality and should be expedited to prevent complications. Risk factors should be identified pre-operatively for better decision-making. Adequate concurrent medical therapy may prevent recurrences. Prolonged follow-up is mandatory to detect late recurrences.

Introduction

Echinococcosis, also known as hydatid disease (HD) or hydatid cyst (HC), is caused by the parasitic cestode Echinococcus. HD has been described by Hippocrates and Aristotle, who had also suggested treatment methods [1]. It remains an important endemic problem in areas around the world where live-stock farming is done [2]. Humans can only be infected by eating eggs passed by an infected dog or other canines. HD is not transmitted from person to person, or by a person eating the meat of an infected animal. The disease is most commonly found in people raising sheep. Human beings are accidental hosts but human infection is estimated to account for more than 95% of about 3 million cases around the globe with 1–3 million disability-adjusted life-years lost per annum because of HD [3]. Cystic echinococcosis (CE) is the most common presentation in humans [4]. The other type, the alveolar echinococcosis (AE), is rarer, with approximately 18,235 new cases per annum, with the majority (91%) occurring in China [4]. High prevalence of HD is seen in the Mediterranean regions, parts of Russia, Central Asia, Australia, parts of South America and Africa [3]. In India, HD is more common in the states of Andhra Pradesh and Tamil Nadu [5]. Humans become hosts, when they are infected by embryonated eggs of the parasite [6]. The liver gets infested the most (Fig. 1a), followed by the lungs [6]. Other unusual sites of thoracic hydatid disease (THD) are the ribs, the pericardium and the heart (Fig. 1b-d). Trans-diaphragmatic migration of the larvae from the liver into the thoracic cavity, transportation of the larvae by chyle and direct infection of the lung by inhalation of eggs have all been postulated as other aetiologies of THD [4].

Fig. 1.

CT of the thorax showing (a) liver hydatid extending into the right hemithorax and a splenic HC, (b) HCs in the pleural cavity extending to the chest wall, (c) HC involving a left rib (arrow), and (d) HC in the right ventricular free wall (arrow)

THD is often asymptomatic or may cause symptoms according to the site of involvement. Computed tomography (CT) is the most valuable diagnostic modality. Magnetic resonance imaging (MRI) and ultrasonographic (USG) examinations may be contributory in the diagnosis. Antibodies directed against specific echinococcal antigens are found only in approximately half of patients with HD [4]. Treatment of HD is essentially surgical, supplemented by medical therapy. Due to a dearth of literature in management of THD in India, a retrospective study was proposed to analyse the surgical outcomes.

Aim and objectives

The primary aim of the study is to evaluate the surgical outcomes in patients who underwent surgery for THD in a tertiary care centre in India. The objectives include the following:

1. To study the demographics of patients with THD who underwent surgery.

2. To assess the pre-operative variables that affected the outcomes after surgery for THD.

3. To formulate a protocol for management of THD in India.

Methodology

The live electronic database of case files of all adult patients who underwent surgery for THD in our institution between 2009 and 2019 was analysed. This study was a retrospective observational study. The approval of the institutional review board was obtained (IRB Min. No. 13220, dated 22–07-2020).

Exclusion criteria

1. Patients less than the age of 15 years.

Statistical analysis

All statistical analyses of various parameters were done using the Excel Worksheet and SPSS version 25 software. All comparative analyses were done by the chi-square test for qualitative variables and Student’s t test for quantitative variables. A ‘p’ value of less than 0.05 was considered significant. Univariate analysis was done to find out the pre-operative factors that predicted surgical outcomes. Multivariate analysis by multiple logistic regression was done for the factors that were found to be significant in univariate analysis.

Pre-operative workup

All patients suspected to have THD on a chest X-ray were evaluated as per a fixed protocol. All of them had baseline blood tests, and CT of the chest and abdomen for confirmation of diagnosis, identification of comorbidities and to rule out synchronous abdominal HD. When the diagnosis was in doubt, MRI scan or an USG examination was carried out as well. Fibreoptic bronchoscopy was done if a neoplasm was suspected or when a major lung resection was considered. During fibreoptic bronchoscopy, a biopsy, direct suction on the lesion, or a wash was avoided if the lesion appeared to be a hydatid, lest the cyst ruptures and causes dissemination of the disease. A pulmonary function test was done only in those cases where lung resection was anticipated. Serological tests were not done as a routine as the absence of antibodies does not preclude the possibility of HD [7]. The pre-operative management included nutritional buildup, cessation of smoking, control of diabetes mellitus, blood transfusions if the haemoglobin level was less than 10 g% and treatment of other comorbidities, if any. All patients were initiated on oral albendazole (10–15 mg/kg/day) and praziquantel (40–60 mg/kg/week) pre-operatively, as soon as the diagnosis was made. Cardiac hydatids were usually diagnosed by echocardiography or MRI.

Criteria to decide the type of surgery

Though pre-operative imaging helped plan the type of surgery to be performed, the final decision was made intra-operatively, based on findings. A lobectomy was performed if the cysts involved more than two-thirds of the lobe, has no aerating salvageable lung tissue in that lobe, or if the remnant parenchyma of that lobe was consolidated or destroyed by secondary infections. In cases with bilateral pulmonary HD, staged thoracotomy was preferred, operating the side which was more extensively affected or complicated first, and then operating on the other side, giving a 3-week interval between the two surgeries, thus allowing the patient to recover functionally between surgeries. Bilateral sequential synchronous excision of the cysts was offered to patients who had only an uncomplicated small superficial cyst on the opposite site. In the presence of a synchronous liver hydatid, a trans-diaphragmatic approach was used for excising cysts involving the superior aspect of the liver (segments 2, 7 and 8 of the liver). Hepatic cysts not accessible trans-diaphragmatically were removed laparoscopically or by a laparotomy. Other synchronous abdominal or systemic hydatids may be excised in the same sitting, or in a staged manner, as per the general surgeons’ or patient’s preference.

Surgical management

All pulmonary HD and pleural HD were approached through a postero-lateral thoracotomy with lung isolation, while the cardiac and pericardial HCs were approached through a midline sternotomy (Fig. 2a). A single dose of intravenous hydrocortisone 100 mg was given at induction of anaesthesia, to prevent anaphylaxis by the hydatid fluid during surgical manipulations. After the thoracic cavity was entered, the pulmonary hydatid was easily identified by the thinning of the pericyst or the overlying inflammation. At times, a digital palpation was necessary to identify a small cyst lying deep within the parenchyma. The aim of the surgery was to evacuate the cyst without spillage, clean up the cavity, and close any bronchopleural fistula (BPF) if present and to obliterate the pericyst cavity. The thinned out area of the pericyst is chosen for the incision. The surgical site was isolated by packing around with surgical pads soaked in a scolicidal solution (0.5% cetrimide) to prevent local implantation of protoscoleces, in case accidental spillage happens. The incision on the pericyst exposed the laminated membranes. If the hydatid membrane was intact, as per the CT, it was delivered out in toto through this incision, with the anaesthetist hyper-inflating the lungs, a technique described by Barrett and Thomas in 1952 [8]. If the membranes had already ruptured inside an intact pericyst, about 5 cc of the scolicidal agent was first injected into the cyst prior to opening it in a controlled manner, to suck the contents out. The thinned out devitalised areas of the pericyst were now excised. The residual cavity was irrigated with and cleaned using the scolicidal solution. The cut edges of the pericyst were plicated with an absorbable suture to control bleeding and air leaks. Any bronchial opening in the wall of the cyst was identified with the lungs ventilating, and closed using non-absorbable sutures. The cavity was capitonnaged using absorbable sutures (Posada’s technique) [9]. Small cysts without air leak were just excised without capitonnage (Ugon’s technique). A wedge resection of the lung was done for some lesions, if they were suitably peripheral. If the cyst had ruptured into the pleural cavity, the resultant empyema, membranes and daughter cysts were evacuated and the lung decorticated in the conventional way (Fig. 2b). The site of the cysts in the lung was identified and dealt with as mentioned earlier. While operating for hepatic cysts, after removing the cysts, biliary fistulae, if any, were closed with absorbable sutures. The empty hepatic pericyst cyst was filled with normal saline and closed along with the adherent diaphragm using interrupted non-absorbable sutures. Throughout the surgery, care was taken to identify and treat anaphylaxis promptly. After excision of the cyst, the pleural cavity was washed thoroughly using the same scolicidal agent followed by 3% saline. The wash was repeated with normal saline to rinse away residual cetrimide and the hypertonic saline in the cavity. Two conventional intercostals drains (ICDs) were placed, one at the apex and one at the base. The patients were extubated on table. The ICDs were connected to negative suction of about 10 cm of water in the post-operative period.

Fig. 2.

Intra-operative photographs showing (a) HC excision from the right ventricular free wall through a sternotomy (arrow), (b) empyema with floating cysts, (c) HC of the posterior chest wall (arrow), and (d) multiple HC studding the entire left pleural cavity

Post-operative management

Post-operative pain relief was provided by intra-operative paravertebral and intercostal infiltration by 0.5% bupivocaine. For the first 48 h only, continuous low-dose intravenous infusion of a narcotic analgesic was given. Epidural anaesthesia was recommended by the anaesthetists for patients undergoing bilateral thoracotomies and was best avoided in the presence of an overt secondary bacterial infection. Narcotic analgesics were supplemented with oral or parenteral non-steroidal anti-inflammatory and analgesic drugs that were continued for a number of days post-operatively as per the patients’ requirements. The parenteral antibiotics, started at the induction of anaesthesia, were continued for 48 h only and an oral antibiotic was continued further, until ICD removal. The anthelmintic drugs were continued in the post-operative period. The ICDs were removed when the air leak stopped and the drainage volume was less than 100 ml/24 h. At the time of discharge, the patients were continued with 3 cycles of oral albendazole of 4 weeks each with a gap of 2 weeks between cycles. Albendazole was prescribed for 3 months continuously if there was a complicated HC or intra-operative spillage. A continuous lifelong course without a break was prescribed to patients with recurrences. Oral praziquantel was prescribed concurrently for all patients for 6 weeks only. These patients had their blood cell count and liver function tests done every 6 months. Since most of the patients were from long distances, they were advised to follow up with a chest X-ray with a local doctor. Follow-up here was recommended only if there was a recurrence of symptoms or if there was evidence of recurrence in the chest X-ray.

Results

Demographic profile

A total of 186 adult patients were included in the study of which 170 (91.4%) were from a rural agricultural background. The mean age was 34.2 years (range: 22 to 70). The male to female ratio was 1.2:1.

Clinical presentation

The commonest symptom was cough with clear expectoration, in 83 (44.6%) patients while 13 (7%) patients were asymptomatic and had incidental diagnosis of the disease in a radiological image. In 37 (19.9%) patients, haemoptysis was the presenting complaint, while 31 (16.7%) presented with chest pain and 14 (7.5%) with dyspnea on exertion. There was a history of undocumented massive haemoptysis in 10 (5.4%) patients. X-ray revealed that in 27 (14.5%) patients, the cyst had ruptured into the pleural cavity. Three patients presented with a pneumothorax including one with a tension pneumothorax. Bilateral lung involvement was seen in 18 (9.7%) patients and multi-lobar involvement in 27 (14.5%) patients. Right lower lobe was most frequently involved as in 56 (30.1%). In 38 (20.4%) patients, the liver was involved synchronously. There were 2 patients who presented with cardiac cysts, 2 with pericardial cysts and 2 with rib involvement (Fig. 2c). The majority of the cysts (50%) were 6–10 cm in size. There were 42 (22.6%) patients with giant cysts (> 10 cm), among who 22 (52.4%) were less than 35 years old. In 7 (16.7%) patients, the giant cyst was ruptured into the pleura at the time of presentation. The other unusual synchronous sites are mentioned in Table 1.

Table 1.

Location of thoracic hydatid cyst

Location	Number of patients	Location	Number of patients
Lung	135 (72.6%)	Lung + liver	38 (20.4%)
Right	94 (50.5%)	Lung + liver + spleen	1
Upper	17 (9.1%)	Lung + liver + adrenal	3
Middle	21 (11.3%)	Lung + liver + ovary	1
Lower	56 (30.1%)	Lung + anterior abdominal wall	1
Left	68 (36.5%)	Lung + thyroid gland	1
Upper	30 (16.1%)	Extra-pulmonary THC	6
Lower	38 (20.4%)	Rib	2
Unilateral & multi-lobar	27 (14.5%)	Pericardium	2
Bilateral	18 (9.7%)	Heart	2

THC thoracic hydatid cyst

Types of surgery performed

In 94 (50.5%) patients, excision was done by Posada’s technique while in 48 (25.8%) patients by Ugon’s technique. The 18 patients (9.7%), who presented with an empyema, required decortication along with the cyst excision. A wedge resection was done in 2 patients, one by video-assisted thoracoscopic surgery (VATS) and one by thoracotomy. In 18 (9.7%) patients, a lobectomy was mandated. Of the 18 (9.7%) patients with bilateral lung involvement, 4 (22.2%) underwent sequential excision in one sitting, while in the remaining 14 (77.8%) patients, the surgeries were staggered. Both the patients who underwent VATS had intact cysts—one had an Ugon’s type of excision and the other had a wedge resection done. Of the 38 (20.4%) patients who had associated liver involvement, 12 (31.6%) had a trans-diaphragmatic approach and the others had a trans-abdominal approach for excision of these cysts (Table 2).

Table 2.

Surgery performed

Surgical procedure	Number of patients	Surgical procedure	Number of patients
Ugon’s technique	48 (25.8%)	Bilateral sequential excision	4 (2.1%)
Posada’s technique	94 (50.5%)	VATS—excision	1
Lobectomy	18 (9.7%)	VATS—wedge resection	1
Cyst excision + decortication	18 (9.7%)	Liver cyst excision	38 (20.4%)
Wedge resection	1	Trans-diaphragmatic	12 (31.6%)
Cyst excision + Thoracoplasty	1	Trans-abdominal	26 (68.4%)

VATS video-assisted thoracoscopic surgery

Post-operative complications

Post-operative complications were seen in 22 patients (11.8%). Four (2.1%) were re-explored in the immediate post-operative period, one for haemorrhage and three to repair major air leaks. An air leak was considered major, if the lung did not expand due to the leak. Seven patients (3.8%) had prolonged minor air leaks (Table 3). In 4 (2.1%) patients, there was excessive serous drainage through ICD, prolonging their hospital stay. The rarer complications encountered are mentioned in Table 3. Of the 4 patients who underwent sequential excision of bilateral HCs in one sitting, 2 developed complications (pneumothorax and acute respiratory distress syndrome (ARDS)). One of our patients suddenly developed shortness of breath with tachypnoea in the third post-operative day. A diagnosis of ARDS was made based on the clinical (PaO₂/FiO₂ ≤ 300) and radiological picture. The patient was successfully managed with non-invasive ventilation. Of the 14 patients who underwent staged excision, only 2 (14.3%) developed complications (air leak and atrial fibrillation). The mean hospital stay was 5.9 days (range 4–22 days). There was single post-operative in-hospital mortality (less than 30 days). Post-operative complications and in-hospital mortality have been considered as adverse surgical outcomes to fit into the multiple logistic regression analysis. Fifteen independent pre-operative variables were analysed by univariate analysis (Table 4). The factors which significantly impacted outcomes were analysed using multiple logistic regression (Table 5).

Table 3.

Post-operative complications

Complications	Number of patients	Clavien-Dindo grade*
Total	22 (11.8%)
Air leak	10 (5.4%)	II
Excessive ICD drainage	4 (2.1%)	IIIa
Pneumothorax	3 (1.6%)	IIIa
Bleeding	1	IIIb
Surgical site infections	1	I
Fungal sepsis	1	V
ARDS	1	II
AF	1	II
Re-explorations	4 (2.1%)	IIIb
Hospital stay (mean with range)	5.9 days (4–22 days)
In-hospital mortality (< 30 days)	1

ICD intercostal drain, ARDS acute respiratory distress syndrome, AF atrial fibrillation

^*Dindo D, Demartines N, Clavien P-A. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg. 2004;240:205–13

Table 4.

Univariate analysis of variables affecting the post-operative outcome

Variable	Number	COR (95% CI) #	P value
Age (< 35 years)	107 (57.5%)	3.45 (1.11 to 10.71)	0.03*
Female	83 (44.6%)	1.45 (0.59 to 3.62)	0.42
Duration of symptoms (> 6 months)	98 (52.7%)	3.24 (1.13 to 9.25)	0.03*
Ruptured cyst	27 (14.5%)	17.5 (6.21 to 49.44)	0.0001*
Bilaterality	18 (9.7%)	2.8 (1.03 to 7.63)	0.04*
Giant cyst (> 10 cm)	42 (22.6%)	6.0 (2.32 to 15.52)	0.0002*
Multi-lobe involvement	32 (17.2%)	2.8 (1.03 to 7.63)	0.04*
Extra-pulmonary involvement	45 (24.2%)	0.98 (0.34 to 2.83)	0.96
Lung resection	20 (10.7%)	0.91 (0.19 to 4.28)	0.91
Smoking	19 (10.2%)	0.40 (0.05 to 3.20)	0.39
Anaemia (Hb < 10 g%)	19 (10.2%)	3.37 (1.074 to 10.58)	0.037*
Hypoalbuminemia (serum albumin < 3.5 g/dl)	11 (5.9%)	1.82 (0.37 to 9.08)	0.46
Associated bacterial infection	56 (30.1%)	3.67 (1.45 to 9.30)	0.006*
Tuberculosis	35 (18.8%)	1.41 (0.48 to 4.14)	0.53
Diabetes mellitus	11 (5.9%)	5.31 (1.41 to 20.01)	0.01*

Hb haemoglobin, #COR crude odds ratio (95% CI, confidence interval)

^* denotes significance

Table 5.

Multivariate analysis of variables affecting the post-operative outcome

Variable	Number	AOR (95% CI)#	P value
Age (< 35 years)	108 (58%)	12.27 (2.007 to 75.03)	0.006*
Duration (> 6 months)	98 (52.7%)	2.64 (0.59 to 11.79)	0.247
Ruptured cyst	27 (14.5%)	15.29 (3.53 to 66.12)	0.0003*
Bilaterality	18 (9.7%)	2.39 (0.38,15.05)	0.23
Multi-lobe involvement	32 (17.2%)	3.24 (0.69 to 15.15)	0.13
Giant cyst (> 10 cm)	42 (22.6%)	8.51 (1.91 to 37.86)	0.005*
Anaemia (Hb < 10 g%)	19 (10.2%)	2.26 (0.38 to 13.46)	0.37
Secondary bacterial infection	56 (30.1%)	3.87 (1.01 to 14.81)	0.048*
Diabetes mellitus	11 (5.9%)	13.03 (1.11 to 152.84)	0.041*

Hb haemoglobin, #AOR adjusted odds ratio (95% CI, confidence interval)

^* denotes significance

Follow-up and recurrence

The mean follow-up was for 14.8 months (1–116 months). Of the 8 patients who underwent surgery for recurrence, 5 had been operated upon in some other centres. The recurrence rate for patients who underwent surgery in our institution was 1.6% (3 patients). Two of these patients had ruptured HC of the lung at index presentation while 1 patient had multiple HCs in the pleura along with the lung hydatid. All these three patients came back to us with recurrences in the pleural cavity (Fig. 2d). All the recurrences occurred after a minimum period of 6 months from the primary surgery despite adequate concomitant chemotherapy.

Discussion

Echinococcosis seems to preferentially infect the younger age group (57.5%), in rural areas, as in other studies, since younger people are perhaps more in close association with canines [6, 10]. The clinical presentation of THD depends upon the size and site of the cyst and complications if present. Pulmonary cysts may be asymptomatic and may be detected incidentally in a routine chest X-ray as in 13 (7%) patients in our series. The most common presentation in our study was cough with clear expectoration 83 (44.6%) followed by haemoptysis 37 (19.9%) confirming to other series [11]. Ten (5.4%) patients presented with a history of massive haemoptysis. Massive haemoptysis may happen when a pulmonary cyst erodes into major vessels like the aorta or the vena cava [12]. Rupture into the pleural cavity will present as pneumothorax, tension pneumothorax, or hydro- or pyo-pneumothoraces, as seen in 27 (14.5%) of our patients. They may erode through the chest wall and present as chest wall masses, necessitans or a fistula, as seen in 3 (1.6%) patients. The lower lobes (50.5%), especially the right one (30.1%), were the commonest to be involved, due to its larger volume and the effect of gravity on the larvae, as they were transported in the pulmonary artery which confirmed with other studies [4, 10]. Our study had 38 (20.4%) patients with both lung and liver involvement as in other studies [11]. The unusual sites for THD reported are the chest wall, diaphragm, heart, mediastinum, pleura and pericardial cavities [13, 14]. In our study, there were 2 patients with cardiac HC in the right ventricular free wall. Cardiac echinococcosis occurs in 0.5–2% of patients having THD, due to the seeding of the cardiac chambers or the myocardium through the systemic venous returns, coronary arteries or from an adjacent structure or cavity [15]. In both the patients, the cyst was excised completely without using cardiopulmonary bypass. CT is usually confirmative for diagnosis (Fig. 3a-d). Atypical CT appearances like hyperdense or solid areas, as some times seen in ruptured, collapsed or infected cysts, may pose a challenge in diagnosis of THD, mimicking a tuberculous infection, fungal infestation or neoplastic lesions [16]. In these cases, MRI and/or USG were useful adjuncts. In 30 (16.1%) patients in our series with such atypical appearance in the CT, T2-weighted MRI was necessary to confirm the diagnosis by identifying the membranes within the cyst and thus differentiating it from other solid or cystic lesions [16] (Fig. 4a, b). The role of USG in THD is limited, except when the lesion is either in, or close to the chest wall, since aerated lung around a cyst decreases discernment [4] (Fig. 4c). Bronchoscopy may show the presence of membranes in the airways (Fig. 4d). Surgery, supplemented by chemotherapy, remains the standard of care for THD [17]. Pre-operative medical treatment using benzimidazoles (albendazole or mebendazole) is recommended as an adjunct to surgery. We, as a protocol, initiated all patients with a diagnosis of THD on albendazole at first contact, in contrast to a study by Mohapatra et al., where pre-operative benzimidazoles were not prescribed [10]. There is a controversy regarding pre-operative albendazole therapy, with authors suggesting points for and against it [17, 18]. Surgery is expedited to avoid complications. In our institute, due to the occasional recurrence (1.6%) of disease in patients who had been adequately treated with surgery and monotherapy with albendazole, praziquantel has been added to the regime the last 2 years. There is literature evidence to suggest the superiority of this combination therapy over monotherapy. Combination therapy seems to be more effective in killing live protoscoleces with no added morbidity [19].

Fig. 3.

Chest X-ray PA view showing (a) an infected HC with air fluid level (arrow), (b) left tension pneumothorax due to a ruptured cyst showing numerous daughter cysts (small arrow) and membranes (arrow), (c) cumbo sign—large cavitary lesion in the left upper zone with internal membrane-like structure containing air that was capped by an air crescent (arrow), and (d) reniform or slot sign—loss of a spherical shape on X-ray with the appearance of small depression due to bronchial rupture (arrow)

Fig. 4.

(a) MRI thorax, axial view, showing the membranes (arrow). (b) MRI of thorax, axial view, showing a left tension pneumothorax due to a ruptured cyst with numerous daughter cysts (arrow). (c) USG showing hydatid membranes (arrow). (d) Fibreoptic bronchoscopy showing membrane in a basal segmental bronchus

In our study, majority of the patients underwent parenchymal preserving surgery, conforming to other studies [10]. Twenty patients (10.7%) required lung resections when an entire lobe or part of the lobe was involved by the cyst or was destroyed due to secondary infections as in other studies [2]. The scolicidal agents suggested in literature for intra-operative use included 3% saline, 10% polyvinylpyrrolidone-iodine and 0.1% cetrimide [20]. There is no consensus regarding which agent is more effective. In our institute, we used cetrimide and 3% saline wash as scolicidal agents and this has shown good results as evident by our low recurrence rates. Though cetrimide is a commonly used scolicidal agent, it is not without complications. Incidences of metabolic acidosis, methaemoglobinemia, acute renal failure and ARDS have been reported [21–23]. In surgical management of bilateral pulmonary HCs, there are two schools of thoughts as to the timing of the second surgery. In our study, the side which was more affected or the side which had developed complication was operated upon first as in 14 (77.8%) of our patients with bilateral disease. A bilateral simultaneous surgery was best avoided in patients with poor lung reserve and in those with severe unilateral secondary bacterial infection, to avoid getting the other side infected. It has been suggested that the operated lung is given about 3 weeks’ time to recover and attain full function before the opposite side is operated upon [24]. Single-stage surgery is preferred by some, since the patient goes under anaesthesia only once. The barotrauma caused by single lung ventilation by itself may rupture a cyst on the non-operated side. The possibility of complications developing due to delay in the treatment is also avoided by a single-stage operation [24]. Denis et al. [25] and Galindo et al. [26] have reported their experiences with single-stage surgery in managing HC with good outcomes. The 4 patients who underwent single-stage cyst excision were young, had small superficial HCs and had a good cardiopulmonary reserve. In patients with synchronous lung and liver involvement, the trans-diaphragmatic approach was used to manage cyst involving the accessible superior segments of the liver. Over the past few years, due to increased application of VATS, many studies tend to show that VATS is a safe and viable option for THD. These studies claim low incidences of complications and quick post-operative recoveries. However, these studies are retrospective in nature with small sample sizes. Hence, further randomized prospective studies are warranted to compare VATS with the conventional thoracotomy [27].

Continuation of chemotherapy post-operatively reduces the risk of recurrence and spread [17, 28]. The currently recommended protocol that we follow for simple uncomplicated cases consists of three cycles of 4 weeks of albendazole with a 2-week gap in between cycles. The 2-week interval between cycles is recommended in literature to avoid the possible adverse effects of albendazole, like hepatotoxicity and bone marrow suppression [17]. There are a few studies that have shown continuous therapy is more efficacious than cyclical therapy with no added adverse effects [17]. The intermittent therapy has the disadvantage of allowing the surviving metacestodes to grow during the gaps [17, 28]. Oral praziquantel was also prescribed post-operatively, once a week, for all patients for 6 weeks, as a part of dual anthelmintic regime in contrast to other studies available from India where only albendazole was administered [10]. The management protocol followed in our institute has been depicted in Fig. 5. In our study, 22 patients (11.8%) developed complications comparable with other reports [2, 29]. Air leak was the most common complication in our study, occurring in 10 (5.4%) patients confirming to other studies [18]. Three of our patients with major air leak immediately after surgery were re-explored promptly for re-suturing of the BPF. These patients had very necrotic pericysts resulting in the sutures cutting through. Air leak lasting for more than 7 days was labelled as prolonged air leak [30]. Six of these patients had minimal prolonged air leaks with fully expanded lungs, and were managed conservatively with judicious management of the ICDs. In three of these patients, the air leaks stopped on the 14^th, the 17^th and the 22^nd post-operative days respectively. The remaining 3 patients were discharged with their ICD in situ, connected to an underwater drainage system. The ICDs were removed subsequently on follow-up as outpatients. One patient underwent a modified Eloesser flap procedure after a period of 3 weeks of ICD drainage, as the underlying lung was necrotic, would not expand and a re-exploration to close the BPF was anticipated to fail. One patient was re-explored in the immediate post-operative period for haemorrhage. This patient had a trans-diaphragmatic approach to excise a lung and liver hydatid. The bleed was from the site of released adhesions in the thorax. There were 4 patients (2%) who had excessive serous discharge from the ICD for which the drains were kept in situ for an average period of 11 days. The reason for this excessive drainage may be due to the intense pleural inflammation caused by cetrimide, used during surgery. The thoracic cavity is usually rinsed thoroughly with normal saline at the end of surgery. The in-hospital death (0.5%) in our study was lesser than that of other studies [31]. A patient, who had undergone splenectomy earlier for a synchronous splenic hydatid, succumbed to fungal empyema and fungemia, despite prompt diagnosis and aggressive treatment, 28 days after the lung surgery. The recurrence rate in patients who were operated upon in our institute was 1.6% (3 patients) which was comparable or lesser than other studies [2, 31, 32]. There were 5 other patients who presented with recurrence after having been operated upon in some other centres. The adequacy of peri-operative chemotherapy in these 5 patients was questionable since no proper records were available. Low recurrence rate in patients operated upon at our centre may be attributed to the early initiation and continuation of adequate and appropriate dual anthelmintics, early surgical intervention and meticulous surgical technique.

Fig. 5.

Management protocol for THD

Patients younger than 35 years of age showed a higher incidence of complications, since the incidence of HD at this age group is high. Diabetes mellitus and associated bacterial infections have shown to affect the surgical outcomes adversely. Aggressive peri-operative glycemic control is known to improve surgical outcomes [33]. Infected HC and empyema might have resulted in more post-operative complications. The characteristics of the cyst which affected the outcomes significantly were size and integrity of the cyst. Giant cysts are known to cause more complications [29]. Patients presenting with ruptured HC, due to the dissemination in the pleural cavity, had a higher incidence of complications. Other statistically insignificant variables which were seen to affect the post-operative outcome were duration of symptoms, presence of anaemia, bilaterality and multi-lobar involvement.

Limitations

The major limitation of the study is its retrospective nature. As most of the patients were from remote rural areas, satisfactory long-term follow-up was not possible. The follow-up duration in our study was 14.8 months, and hence recurrence rates and mortality over long term cannot be established.

Conclusion

Surgery for THD could be done with negligible morbidity and mortality. Our experience with managing THD with a streamlined protocol has provided us good results and can be followed as protocol for management of THD. Awareness of pre-operative risk factors will improve outcomes after surgery for THD.

Author contribution

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Aamir Mohammad and Santhosh Benjamin. The first draft of the manuscript was written by Aamir Mohammad and all authors commented on previous versions of the manuscript. The final manuscript was written by Aamir Mohammad and Birla Roy Gnanamuthu. All authors read and approved the final manuscript.

Funding

None.

Declarations

Ethics approval

The approval of the institutional review board has been obtained.

Informed consent

Written consent for studies and publication were obtained from the patients prior to the surgery.

Human and animal rights

The study has been performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.

Conflict of interest

The authors declare no competing interests.