Management of small bowel obstruction in the third trimester

Abstract

Small bowel obstruction (SBO) in pregnancy is exceedingly rare. Management of SBO in the third trimester may pose particular challenges, as clinicians must determine whether or not the delivery of the fetus is indicated. In this report, we review the case of a patient in her mid-20’s with no prior surgical history who presented with nausea and vomiting at 34 weeks of gestation and was ultimately diagnosed with an SBO. Following expectant management during the initial 4 days of inpatient admission, the patient subsequently underwent an exploratory laparotomy at 35 weeks without concurrent delivery. She was monitored for the remainder of her pregnancy with non-stress tests to evaluate fetal status and eventually underwent induction of labour at 39 weeks, resulting in a successful vaginal delivery. Herein, we review the challenges related to the diagnosis and management of SBO in pregnancy, as well as the maternal–fetal outcomes in the setting of SBO in the third trimester.

Background

Small bowel obstruction (SBO) in pregnancy is a rare presentation with an incidence spanning a wide range from 1/1500 to 1/100 000.^{1 2} It is often accompanied by symptoms of abdominal pain, nausea and vomiting.² Timely diagnosis and management of obstruction in pregnancy is critical as SBO can be associated with significant maternal and neonatal mortality.^{3 4} Postsurgical adhesions are the most commonly reported cause of SBO, noted in about 50–70% of all cases.⁵ The diagnosis and management of SBO in pregnancy is a challenging dilemma particularly within the third trimester when the gravid growing uterus can interfere with access, and fetal monitoring intraoperatively during open abdominal surgery can be more complex and less understood than basic bowel surgery. SBO secondary to congenital adhesions is even more rare and is a diagnosis that can only be made at the time of surgery.

Literature on the presentation, diagnosis, management and outcomes for SBO in the third trimester of pregnancy is limited. This case report discusses a patient with a third-trimester SBO, highlights the challenge of diagnosis and reviews the literature about presentations of SBO in the third trimester, management plans and associated maternal and neonatal outcomes.

Case presentation

A patient in her mid-20s, G2P1001, with a prior term vaginal delivery and no significant obstetrical, medical or surgical history presented at 34 weeks 1 day gestation for evaluation of ongoing nausea and vomiting in pregnancy. This was the patient’s fourth presentation of similar symptoms since the onset of her pregnancy. She reported an inability to tolerate intake of both solids and liquids, as well as a persistent, sharp epigastric pain that radiated across her abdomen that was worse after vomiting. Oral antiemetics and H2-blockers that were prescribed to the patient after her prior hospital admissions were not effective in alleviating her symptoms. In light of her intolerance of oral intake and significant abdominal pain, the decision was made to admit the patient for supportive care.

Investigations

On admission, the patient’s heart rate, blood pressure, respiration rate and body temperature were all within normal limits. A complete blood count and basic metabolic panel—to evaluate electrolyte status—were obtained, and the results were within normal limits. The abdominal assessment revealed a distended abdomen that was diffusely and mildly tender to palpation. There was no guarding nor rebound tenderness. A right-upper quadrant sonogram was first performed to rule out a gallstone aetiology in the setting of abdominal pain, nausea and vomiting. The ultrasound scan revealed gallbladder sludge but was otherwise unremarkable. The patient was made nil per os, and administered intravenous fluid boluses for rehydration and pain medicine including tylenol or intravenous morphine as needed.

On day 2 of hospital admission, the patient shared with the medical team that she had not had a bowel movement nor passed flatus for at least 3 days. A bowel regimen composed of polyethylene glycol and Dulcolax was initially started to rule out and resolve constipation or an obstructive process as an aetiology. The patient however failed to pass flatus or have a bowel movement subsequently. Serial clinical abdominal examination continued to reveal a distended and mildly tender abdomen. The patient remained afebrile with no increase in the heart rate or respiratory rate, and no evidence of a septic abdomen. No hernia was appreciated on abdominal examination. In the absence of leucocytosis or sudden onset pain, appendicitis was lower on our differential. An abdominal X-ray was performed to evaluate for dilated, obstructed bowel in the setting of abdominal pain and failure to pass flatus. The X-ray demonstrated distended loops of the small bowel. Expectant management was initially implemented for the abdominal symptoms, of which the cause was not known and remained under investigation. However, on day 4 of hospital admission, the patient was noted to have worsening abdominal distension and continued vomiting. The decision was made to place a nasogastric tube for decompression. Immediate output of approximately 2 L of bilious content was noted and the patient reported mild symptomatic relief. Nutritional services were consulted to evaluate the patient’s candidacy for total parenteral nutrition and the acute care surgery team recommended a water-soluble contrast (Gastrografin) follow-through examination. Serial abdominal radiographs up to 24 hours after initial contrast administration did not demonstrate Gastrografin in the colon. This was confirmative of small bowel obstruction.

Treatment

A diagnosis of SBO was made. As there was no history of prior surgery and no hernia on examination, with progressive distension, large volumes of nasogastric drainage and a failure of resolution, immediate surgical intervention was necessary. Interdisciplinary meetings with the maternal fetal medicine and acute care surgery departments were conducted to discuss surgical approaches (eg, laparoscopy vs laparotomy) and the feasibility of operative intervention without delivering the patient. Both teams felt that exploratory laparotomy with continuous intraoperative fetal monitoring could be safely performed. The patient received a full course of antenatal steroids for fetal lung maturity and on day 7 of hospital admission she was taken for surgery. A subxiphoid incision measuring approximately 6 cm was made. The ligament of Treitz was identified and the bowel was examined distally. An adhesive band from the ileum to the mesentery was noted under which the proximal bowel had herniated causing a complete obstruction. The bowel did not show evidence of ischaemia. The band was divided, and the bowel was re-examined from the ligament of Treitz down to the ileocecal valve. No further lesion was noted. The procedure took a total of 60 min from induction of anaesthesia to skin closure. The obstetrical team was present for both the induction of anaesthesia and the duration of the procedure to assist with fetal monitoring. Continuous fetal heart tracing was possible throughout the case due to the supraumbilical location of the incision and the fixation of the transducer to the patient’s abdomen using a large adhesive dressing. The fetal heart tracing remained reassuring for the duration of the case, showing a fetal heart rate baseline of 135 beats per min, moderate fetal heart rate variability, positive fetal heart rate accelerations and no fetal heart rate decelerations consistent with normal parameters (normal range 110–160 beats per min). At the conclusion of the procedure, the patient was returned to the antepartum unit for postoperative recovery and monitoring.

Outcome and follow-up

On postoperative day 1, the patient experienced significant symptomatic improvement. She received total parenteral nutrition, scheduled analgesics and a bowel regimen (polyethylene glycol and Dulcolax) while awaiting the return of bowel function. Nasogastric tube output was minimal during this time. During postoperative day 1, the patient had continuous fetal heart rate monitoring for 24 hours and the fetal heart tracing was persistently within normal parameters: baseline of 130 beats per min, moderate variability, positive accelerations and no decelerations. Subsequently, thereafter, she had two times per day non-stress testing (NST) for fetal monitoring and the NSTs were reactive, hence, within normal limits. She had a passage of flatus on postoperative day 3, and her diet was slowly advanced. The patient had a bowel movement on postoperative day 4 and her nasogastric tube was removed. On postoperative day 5, the patient was tolerating a regular diet, reported excellent pain control with an oral analgesic regimen and, thus, was deemed stable for discharge. In addition to routine third-trimester prenatal care visits, biweekly NSTs were scheduled to evaluate fetal status. As per the recommendation of the maternal fetal medicine team, induction of labour was scheduled for 39 weeks gestation. There was no indication to deliver sooner than 39 weeks as there were no uterine incisions made that would necessitate earlier delivery. The patient was 3 cm dilated at the time of induction, so oxytocin was initiated to help augment labour and initiate uterine contractions. She subsequently had an uncomplicated vaginal delivery that day of a healthy newborn. Her postpartum course was uncomplicated. On the second postpartum day, she and her baby were discharged.

Discussion

We described the case of small bowel obstruction diagnosed in the third trimester of pregnancy which was surgically managed via exploratory laparotomy. The patient was subsequently induced at 39 weeks of gestation and had an uncomplicated vaginal delivery. This was a unique case in which a patient had SBO with no obvious cause. The diagnosis was unexpected and delayed as investigations were performed to determine the cause of evolving obstructive symptoms.

Management of SBO in the third trimester can be challenging when determining timing and route of delivery. Urgent surgical intervention is compounded by advanced pregnancy and the potential risk to the fetus. SBO in the third trimester of pregnancy is extremely rare. SBO due to a congenital adhesion is an extremely difficult clinical diagnosis. In this case, the patient underwent urgent laparotomy as soon as the diagnosis of non-resolving SBO was made. The cause of SBO was discovered during surgery. We conducted a literature review using PubMed, Embase, Ovid MEDLINE and additional hand searches. Search terms included ‘third trimester’ and ‘pregnancy’ and ‘case’ and ‘small bowel obstruction’. We generated a total of 53 unique detailed cases of SBO in the third trimester of pregnancy excluding our case (figure 1). Factors from the literature review cases^6–58 included maternal age, gestational age at the time of presentation, presenting symptoms, imaging modalities used, inpatient management approach, surgical route if applicable, intraoperative fetal heart rate monitoring if applicable, delivery timing, route of delivery, maternal outcomes, fetal outcomes and length of hospitalisation as outlined in the (online supplemental table 1). The data were extracted to a custom-made inclusive table outlining all the variables highlighted in table 1. Means and SD values were calculated for continuous variables and percentages were calculated for categorical variables.

Figure 1.

Flow diagram of literature search.

Table 1.

Summary of the literature search for SBO cases during the third trimester

		Cases (%): total 53
Maternal age (years; mean±SD)		29.5±6.4
Gestational age (weeks; mean±SD)		32±3
Presenting symptoms	Abdominal pain Vomiting Nausea Abdominal distension Constipation Diarrhoea	53 (100) 32 (60.4) 25 (47.2) 8 (15.1) 3 (5.7) 2 (3.8)
Diagnostic imaging	CT X-ray MRI Not mentioned	20 (37.7) 18 (34.0) 12 (22.6) 13 (24.5)
Aetiology of SBO	Volvulus Hernia Ischaemia Adhesions Meckel’s diverticulum Malrotation Intussusception Cancer Intestinal knot	15 (28.3) 11 (20.8) 9 (17.0) 8 (15.1) 6 (11.3) 5 (9.4) 4 (7.5) 2 (3.8) 1 (1.9)
Surgical management	Yes, antepartum Yes, postpartum No	40 (75.5) 8 (15.1) 5 (9.4)
Surgical method, n=48	Exploratory laparotomy Laparoscopy converted to laparotomy Laparoscopy	41 (85.4) 4 (8.3) 3 (6.3)
Timing of delivery	Concurrent caesarean section Caesarean section, full-term Caesarean section, preterm IOL, full-term IOL, preterm SVD, full-term SVD, preterm Unspecified	17 (32.1) 5 (9.4) 3 (5.7) 6 (11.3) 5 (9.4) 10 (18.9) 3 (5.7) 4 (7.5)
Maternal outcome	Survived Maternal death	49 (92.5) 4 (7.5)
Fetal outcome	Survived, full-term Survived, preterm Neonatal demise Unspecified	22 (41.5) 24 (45.3) 4 (7.5) 3 (5.7)
Length of hospitalisation, (days; mean±SD), n=26		11.4±6.6

IOL, induction of labour; SBO, small bowel obstruction; SVD, spontaneous vaginal delivery.

The mean gestational age at diagnosis in the third trimester was 32±3 weeks. All patients presented with symptoms of abdominal pain. Other presenting symptoms included nausea, vomiting, distension, constipation and/or diarrhoea. Our patient was diagnosed at 35 weeks with symptoms of nausea and vomiting. A diagnosis in the preterm period can bring challenges regarding the management of SBO while considering the timing of delivery to help alleviate symptoms. The cause of SBO is important, adhesional obstruction may resolve with nasogastric decompression and intravenous fluid resuscitation. Non-adhesional causes are likely to require immediate surgical intervention. Where laparotomy is indicated, it is critical to weigh the risks and benefits of fetal delivery. In our case, some considerations we reviewed were the risks of fetal delivery in a preterm period, which included associated prematurity and the need for neonatal intensive care unit admission. Benefits of fetal delivery, on the other hand, included the elimination for the concern for fetal monitoring and concern for fetal well-being while performing workup or surgical management under general anaesthesia for a patient with an unknown cause of complete bowel obstruction. Ultimately, as we weighed risks and benefits, and as we devised ways to perform fetal monitoring intraoperatively while addressing aetiologies for bowel obstruction, we decided—with the agreement of the patient—that the risk of prematurity in this case outweighs surgical risks as long as intraoperative monitoring was feasible. Such conversations and risk-benefit balance helped us reach our decision to avoid fetal delivery at the time of surgical intervention.

Imaging in obstetrics is always considered carefully. Imaging, however, should not be denied to pregnant individuals when necessary for life-saving interventions.⁵⁹ Due to the infrequency of SBO in pregnancy, there is a lack of agreement on the best imaging protocols. The literature showed diversity in imaging used to help guide diagnosis and management when SBO was suspected. CT was performed in 37.7% of cases, followed by X-ray in 34.0% of cases, followed by MRI in 22.6% of cases. It is important to note that, while, in our case, we sufficed with x-ray to help guide diagnosis and management, if further imaging is required with contrast, the benefit in such cases could outweigh the risk of contrast in any trimester.10 20 26 28 In general, the overarching principle for any imaging procedure is to begin with the least invasive tool and advance as required. Typically, ultrasound is the initial choice due to its safety, followed by MRI to avoid radiation exposure. Plain film X-ray followed by a CT scan may be considered subsequently if needed, with plain X-ray carrying a significantly smaller dose of radiation to achieve the diagnosis compared with the CT scan.

The aetiology of bowel dilatation can be categorised into mechanical and non-mechanical causes, as outlined in table 2.^60–65 These causes are not limited to a specific trimester and can manifest at any point during pregnancy. The most common causes of small bowel obstruction in pregnancy reported in the literature were volvulus, hernia, ischaemia and adhesive disease—thus, a history of previous abdominal surgery is important to note. Our patient had no history to suggest adhesional obstruction, indeed, the diagnosis of complete bowel SBO was made as a result of investigations for non-resolving abdominal symptoms. The cause of SBO was determined intraoperatively. Our patient had an adhesive band from the ileum to the mesentery—suspected to be a remnant of the omphalomesenteric duct—under which the proximal bowel had herniated, resulting in a complete obstruction. The presence of such an adhesive band is a rare and uncommon cause of small bowel obstruction.

Table 2.

Common mechanical and non-mechanical causes of bowel dilatation in pregnancy^60–65

Mechanical	Non-mechanical
Luminal: Bezoar Impacted stool Mural: Congenital atresias Diverticular stricture Intussusception Malignancy Extra-mural: Adhesions Hernia Impacted stool Intestinal knot Malrotation Meckel’s diverticulum Volvulus	Structural: Aganglionic bowel Disease complication: Ileus Ischaemia Narcotic bowel syndrome Ogilvie’s syndrome Toxic megacolon

It is important to think of SBO as either complete or partial. This is key as one considers conservative or surgical management accordingly. A congenital band, such as our case, or an obstructive hernia may result in complete obstruction which requires immediate intervention. Expectant management is recommended in cases where the resolution of the obstruction is probable without surgery—usually where there is partial or adhesional obstruction. In the literature, the majority of patients in the third trimester of pregnancy required surgical intervention, either during the antepartum period (75.5%) or the postpartum period (15.1%). Only 9.4% of cases were successfully managed non-operatively. Non-operative management was attempted as the initial approach in nearly all cases before resorting to surgical intervention. In the context of pregnancy, it may be beneficial to have an algorithm guiding the next steps for patients suspected of small bowel obstruction. For instance, Gudbrand et al developed a flowchart illustrating guidelines for managing pregnant patients with suspicion of internal hernia, and consequently, small bowel obstruction following Roux-en-Y gastric bypass surgery.⁶⁶ Such algorithms can greatly assist obstetricians facing similar patient cases, expediting the management and treatment of suspected small bowel obstruction. As a non-operative approach, that is, expectant management via nasogastric tube decompression, is only applicable for cases of partial bowel obstruction or incomplete adhesional obstruction, establishing a diagnosis of complete obstruction, confirming non-resolution or disease progression is important. Partial bowel obstruction can be managed with nasogastric tube decompression and intravenous fluids, is likely to resolve and is confirmed with contrast follow-through. While we had no evidence of bowel ischaemia on clinical examination or at surgery, we suspected and ultimately confirmed that our case was one of complete bowel obstruction as the patient’s symptoms progressed. Intraoperative findings showed an adhesive band from the ileum to the mesentery under which the proximal bowel had herniated causing a complete obstruction. The distal position of the obstruction in our case may correlate with the gradual evolution of symptoms—making the diagnosis challenging but perhaps mitigating the onset of ischaemia. Signs of bowel ischaemia (evidence of acidosis, leucocytosis, renal failure and peritonitis) warrant urgent surgical intervention.

Among all reviewed cases of SBO in the third trimester, 32.1% of patients underwent concurrent caesarean section at the time of exploratory laparotomy for definitive management of SBO. This accounted for 42.5% of all cases who underwent surgical intervention in the antepartum period. Hence, nearly half of the patients who required surgery in the third trimester ended up delivering their infants concurrently. This was a point of debate among our obstetrics, general surgery and maternal and fetal medicine providers. While delivery was not warranted, given a stable fetal status throughout the SBO encounter, the question was raised as to whether it is better to deliver simultaneously for improved infant outcomes. A secondary debate among team members revolved around intraoperative fetal monitoring, particularly if the surgery required an extensive period under general anaesthesia. The decision for or against concurrent newborn delivery was made intraoperatively when possible fetal monitoring could be confirmed. Given the relatively cephalad nature of the supraumbilical incision made, we were able to perform continuous intraoperative fetal monitoring which confirmed reassuring fetal status throughout the case. The monitor was ultimately anchored to the patient’s abdomen using a large Tegaderm. This did not interfere with visualisation by the surgical team nor require additional individuals to hold the fetal heart monitoring probe in place (figure 2). Of note, however, the obstetrics team was on standby in the operating room and ready if delivery was indicated. Being able to perform continuous intraoperative monitoring played a substantial role in deciding against concurrent newborn delivery. While there are no known guidelines on how to best perform continuous intraoperative monitoring, being able to anchor the fetal monitor to the patient’s abdomen provided a secure and reliable method to assess fetal status continuously throughout the procedure. It is noteworthy that only one case in the literature specifically stated that continuous fetal heart monitoring was performed intraoperatively,⁴⁹ with no clarification on the method used. Therefore, we present a detailed description of the method of intraoperative monitoring that may be used for all pregnant patients undergoing lengthy procedures in the third trimester or any week following fetal viability. Once we established a way to perform fetal monitoring intraoperatively, we felt reassured that we are able to monitor fetal status and evaluate for fetal distress, and most importantly intervene as necessary if caesarean delivery was indicated for non-reassuring fetal heart tones.

Figure 2.

Illustration of intraoperative fetal monitoring (this figure was drawn by author MM).

In terms of maternal outcomes, maternal death was reported in four cases in the literature.20 25 34 42 In three of the cases, immediate deterioration of the patients was noted shortly after presentation necessitating emergent surgical management. Surgical findings included a combination of bowel ischaemia, infarction and necrosis^{20 25 42} indicating that ischaemic complications of obstruction were associated with adverse outcomes. In one case, the patient presented with signs of an acute abdomen and died while being evaluated in the emergency department.³⁴ An autopsy was subsequently performed showing intestinal obstruction at the proximal jejunum with necrosis, perforation and peritonitis (a high obstruction with obvious signs of ischaemic complications).³⁴ In summary, however, maternal demise is not common and timely management has shown successful outcomes. In our case, we were able to frequently monitor maternal heart rate, respiratory rate, oxygen saturation and temperature, while obtaining laboratory workup as indicated, all of which helped with timely maternal evaluation for any signs and symptoms of ischaemia, sepsis or organ failure. Additionally, it is worth pointing out that one of the reasons for our delayed diagnosis was the fact that our patient did not have adverse events as ischaemic complications; but this is also why our patient had favourable outcomes.

Regarding fetal outcomes, fetal death was noted in four cases, two of which were concurrent with maternal demise.^{20 42} Fetal demise was noted during workup prior to surgical management in both cases. The other cases were: one in the setting of SBO workup with initial reassuring fetal heart tones on admission¹⁴ and the second in the setting of the patient’s decision to abandon the fetus, who was noted to have hydrocephalus, and thus underwent a mid-trimester-induced abortion.⁵⁸ The majority of fetuses, otherwise, survived and delivered either full-term (41.5%) or preterm (45.3%). Our case describes a successful full-term vaginal delivery after induction of labour with no adverse maternal or neonatal outcomes. Once again, being able to monitor fetal heart rate whether preoperatively, intraoperatively or postoperatively, allowed us to be reassured regarding fetal status and be ready for any necessary interventions as indicated.

Lastly, in terms of length of hospitalisation, while the majority of cases did not specify the duration of hospitalisation, among the 26 cases that reported the duration, the average hospitalisation for SBO in the third trimester was noted to be 11 days (±6). Our case falls within the same window where our patient was discharged on hospital day 11, postoperative day 5, in stable condition. Of note, the perioperative care approach we took was very cautious, particularly in terms of timing of the nasogastric tube removal. Many would suggest removal as soon as possible after surgery with an early return of oral intake. Given our patient’s preoperative complex course, we found ourselves more cautious with her care postoperatively. While the patient had an uneventful recovery, the process could indeed have been expedited with sooner tube removal and potentially shorter length of stay.

In conclusion, small bowel obstruction in the third trimester of pregnancy is a rare occurrence and should be diagnosed and managed urgently before complications of bowel ischaemia and threats to fetal viability ensue. We here described a case of a patient with SBO resulting from a congenital adhesion who required surgical intervention. The patient had no clinical or operative evidence of bowel ischaemia. This may have both delayed the diagnosis and improved outcome. We highlighted the challenges of intraoperative management and emphasised the facility of intraoperative fetal monitoring without delivery. While reporting bias is a limitation in the literature review, we here attempted to also highlight a summary of the diagnosis and management of pregnant patients in the third trimester with suspected SBO while comparing our case management to that of the literature. The literature indicates that patients with ischaemic complications of obstruction have adverse outcomes. Concurrent caesarean delivery during exploratory laparotomy is not always necessary, especially when continuous fetal monitoring is possible intraoperatively. Continuing pregnancy to full term and subsequent vaginal delivery is possible and encouraged if antenatal fetal surveillance is feasible and reassuring.

Learning points.

• Small bowel obstruction in the third trimester of pregnancy is a rare occurrence and should be diagnosed and managed in a timely fashion.

• If surgical management is indicated, continuous intraoperative fetal monitoring is possible.

• Concurrent caesarean delivery during exploratory laparotomy is not always necessary.

• Continuing pregnancy to full term and subsequent vaginal delivery is possible and encouraged if antenatal fetal surveillance is reassuring.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).