Small bowel volvulus versus adhesive small bowel obstruction: a diagnostic dilemma in a 19-year-old woman

Abstract

Small bowel volvulus (SBV) is often challenging to diagnose. Research suggests that the clinical presentation of this disease is often very similar to other more common causes of small bowel obstruction (SBO) such as intraabdominal adhesions and no single preoperative diagnostic study is sensitive or specific enough to identify this rare cause of mechanical SBO. This report describes a case of a 19-year-old woman who presented with irretractable vomiting and abdominal pain secondary to SBV. This case is unusual as her history of recurrent adhesive SBO presented a diagnostic dilemma that required a higher degree of clinical suspicion to tease these differential diagnoses apart. She underwent laparoscopy which facilitated successful detorsion and resection of the floppy tongue of jejunum. This report aims to increase the awareness among surgeons.

Background

Adhesive small bowel obstruction (SBO) is the most common cause of mechanical obstruction in the developed world, accounting for 65%–70% of such presentations.¹ In a patient with signs of SBO and a history of adhesive SBO, Occam’s razor may prompt the same diagnosis. Here we present a case of primary small bowel volvulus (SBV) presenting as acute SBO in a woman with a history of adhesive SBO. There are certainly many learning points from this case such as the importance of being aware of red flags that may raise suspicion of SBV, which is a rare but important time critical surgical emergency.

Case presentation

A 19-year-old woman presented with a 1-day history of colicky abdominal pain, nausea vomiting and obstipation on a background of multiple previous presentations for adhesive SBO after a laparotomy/small bowel resection as a neonate for duodenal atresia. Both previous presentations for adhesive SBO were managed conservatively with nasogastric (NG) tube decompression and Intravenous fluid therapy.

She was otherwise a fit and well university student with no other significant medical history.

On examination, she appeared in distress even after successful NG tube placement. Light green bilious gastric contents were freely draining from the NG tube. Physical examination recorded a mildly raised heart rate but all other vital signs were within normal limits. Her abdomen was distended, tympanic and generally tender. There were no hernias palpable. Colicky episodes of abdominal pain were observed which caused great distress and required copious amounts of Intravenous opioid medications.

Investigations

Initial investigations included blood tests. Haemoglobin was within normal limit at 127 g/L (110–150 normal range) but white cell count was elevated to 12.4 (5.0–10.9 normal range). Electrolyte and liver function tests were all within normal limits and lactate was slightly elevated to 1.9 (<1.1 normal range).

CT of the abdomen and pelvis was performed with contrast demonstrating dilated small bowel loops with multiple air fluid levels. There was a transition point at the right of the umbilicus which suggested SBO.

Differential diagnosis

SBO secondary to intraabdominal adhesions was the most likely diagnosis given previous surgical history and multiple previous presentations with adhesive SBO. However, considering the patient’s pain and distress, there was clinical suspicion mechanical SBO with vascular compromise. Closer review of the CT images revealed a partial ‘whirl-like sign’ of the mesentery, raising the suspicion of SBV (figure 1). While the prospect of intestinal malrotation was entertained, the typical positioning of small bowel made it less likely.

Figure 1.

CT images that show a partial ‘whirl-like sign’ on the right of the umblicus.

Treatment

With this clinical suspicion, the patient proceeded to an emergency laparoscopy which showed SBV involving a short segment of jejunum (figure 2). After detorting the small bowel, close inspection revealed no areas of compromise. However, considering the floppy tongue of small bowel and the presentation, decision was made to resect it to prevent recurrence. The patient made a swift uncomplicated recovery and was discharged post-operatively on day 2.

Figure 2.

Intraoperative pictures demonstrating the volvulus (L) causing proximal obstruction and dilatation (R) with collapse of small bowel distally.

Outcome and follow-up

At the 4-week post-operative review, the patient reported no further symptoms. Wounds were well healed and she was discharged back to the care of her general practitioner.

Discussion

SBV is a rare surgical emergency that clinicians need to be aware of when faced with a patient with abdominal pain. Based on the Latin word ‘volvere’ which means to roll or turn, SBV indicates a twisting of the small bowel around its mesentery and blood supply, leading to mechanical intestinal obstruction and, more importantly, vascular compromise, ischaemia and finally necrosis. It can be categorised as primary or secondary volvulus.²

Primary or idiopathic SBV is rare in Western countries.³ With a higher incidence among Asian, Middle Eastern and Central African communities, it is hypothesised that volvulus is precipitated by the ingestion of great amounts of fibre-rich foods in a short time.^{3 4} In particular, consumption of such foods after prolonged fasting—a prime example being Muslims during the fasting month of Ramadan—predisposes forceful peristalsis that twists the small bowel around its mesentery.⁴

Secondary SBV, on the other hand, has been attributed to acquired conditions: most commonly post-operative adhesions, tumours, congenital anatomic anomalies and internal hernias.^{2 5 6} Rarely, it can come about as a complication of intestinal malrotation in adults. The failure of the full 270° counter-clockwise rotation during embryonic development leads to malpositioning of small bowel. This also creates a narrowed mesenteric base with floppy tongues of bowel prone to twisting around the mesentery.⁷ In addition, there are often associated bands of Ladd: fibrous peritoneal adhesions between the medialised caecum and the right lateral abdominal wall.⁷ These bands on their own may potentiate internal hernias, which ought to be a close differential diagnosis in this patient group.⁷

To aid diagnosis and differentiation from other causes of SBV, pathognomonic CT findings of malrotation with SBV have been described. Apart from the whirl of mesentery around the superior mesenteric artery (SMA) axis, the abnormal small bowel positioning is a key finding—with the duodenal-jejunal junction failing to cross the midline or lying below the level of the duodenal bulb.^{7 8} In an emergency, this would require the Ladd’s procedure to devolve the affected bowel and divide the congenital adhesions before placement of bowel back into the abdominal cavity.⁸

As mentioned, CT has become an important investigative modality in the diagnosis of all types of SBV. First described by Fisher, the presence of a ‘whirl sign’ on axial CT slices should raise suspicions of SBV.⁹ While some studies have questioned its specificity and even revised the sensitivity of the whirl sign in SBV diagnosis down to 64%,¹⁰ it is still important to be aware of this sign and the other radiological signs associated with SBV. This includes the ‘beak sign’ which represents the shape of a hooked beak formed by the sharp tapering of collapsed bowel at the transition point at the site of volvulus.¹¹ Furthermore, radiological signs of vascular congestion in the affected mesenteric vessels have also been described as secondary findings that may support the suspicion of bowel ischaemia. With the increasing accessibility of CT-angiograms, the ‘barber pole sign’ has also been described to depict the twisting of mesenteric vessels in the volved loop of mesentery.^{11 12}

Due to its time critical nature, any clinical or radiological suspicion of volvulus requires urgent operative intervention to minimise any risk of intestinal ischaemia. Both open or laparoscopic evaluation and management of this condition have been reported. Intraoperatively, detorsion (untwisting) of the involved bowel is urgently required to restore the compromised vascular supply. Among the cases reported so far, some of them have reported that this devolution is often the only manoeuvre needed. However, given a reported 3.5% recurrence rate,⁶ some authors have advocated that some form of intestinal fixation or even resection of that redundant loop of small bowel be undertaken as well to avoid recurrence.²

This is a case of primary SBV in the presence of other potential causes of mechanical SBO, that is, post-operative adhesions which could have muddied the clinical picture. This diagnostic challenge is an important lesson to all clinicians that while Occam’s razor and the rule of probability often present a possible diagnosis, careful evaluation of the patient and investigations are needed to ensure patient safety. As demonstrated, the challenge with preoperative diagnosis lies in the non-specific symptoms which makes it difficult to tell this apart from other less urgent surgical causes of SBO such as adhesions. Abdominal pain out of proportion should always alert clinicians to the possibility of vascular compromise from a volvulus.⁵

Patient’s perspective.

Patient

After having had this (adhesive SBO) for so many times in the past, when the pain started I just thought ‘it’s the same old thing again’. However, the pain was much worse than before and when the doctor told me that it was something different, it made me scared. I wasn’t expecting an operation and to think that there was the potential to need more bowel taken out was scary. (However), after hearing about what they found though … I’m glad it was picked up early.

Patient’s mother

I’m thankful for how things were picked up early and that she was able to leave hospital after just 3 days! Looking back, I wonder if previous episodes of tummy pain could have been related to this twist. Regardless, I’m happy to put this behind us and hope that this won’t happen again!

Learning points.

• Small bowel volvulus (SBV) is a time critical surgical emergency that clinicians must consider when faced with a patient with abdominal pain.

• Preoperative signs to distinguish SBV from other causes of mechanical small bowel obstruction can be subtle. Nevertheless, they include radiological signs such as whirl-like sign or barber pole signs.

• The patient with abdominal pain out of proportion should always raise suspicions of bowel ischaemia.

• SBV necessitates urgent operative intervention: devolution alone versus fixation/resection of the redundant loop of small bowel given an estimated 3.5% recurrence rate.