Volvulus

01Pathophysiology

Volvulus occurs when a segment of bowel rotates around the axis of its own mesentery. This rotation produces two simultaneous problems: a closed-loop bowel obstruction (where both the proximal and distal ends of the segment are occluded) and mesenteric vascular compromise. The closed-loop mechanism is what makes volvulus dangerous and distinguishes it from a simple adhesive obstruction, because the trapped segment cannot decompress in either direction, and the ongoing secretion of fluid into the lumen causes rapid distension.

As the bowel distends within the closed loop, intraluminal pressure rises and eventually exceeds capillary perfusion pressure. Venous outflow is compromised first (because veins are thin-walled and collapse at lower pressures than arteries), leading to congestion, edema, and hemorrhagic infarction of the bowel wall. If the twist is tight enough, arterial inflow is also cut off, resulting in transmural ischemia, gangrene, and perforation. Perforation of ischemic bowel leads to fecal peritonitis, sepsis, and high mortality.

Sigmoid volvulus is the most common type in adults, accounting for roughly 60 to 75 percent of all colonic volvulus cases. It occurs because the sigmoid colon has a long, redundant mesentery with a narrow base of attachment, making it susceptible to twisting. Chronic constipation and colonic dilation (as seen in neuropsychiatric patients or those with Chagas-related megacolon) elongate the sigmoid further and predispose to rotation.

Cecal volvulus occurs when the cecum and ascending colon are abnormally mobile due to incomplete embryologic fixation to the retroperitoneum. This allows the cecum to fold upward and medially (cecal bascule) or twist axially around the ileocolic vessels.

Midgut volvulus in neonates is fundamentally different. It is caused by intestinal malrotation, a failure of the normal 270-degree counterclockwise rotation of the midgut during fetal development. This results in a narrow mesenteric pedicle (the base of the superior mesenteric artery), around which the entire midgut can twist. The consequence is catastrophic: the superior mesenteric artery (SMA) is occluded, threatening the blood supply to the entire small bowel from the duodenum to the mid-transverse colon. Additionally, Ladd bands (peritoneal bands running from the malrotated cecum across the duodenum) can cause extrinsic duodenal obstruction independent of the volvulus itself.

02Classification and Clinical Manifestation

03Diagnostic Workup

For sigmoid volvulus, the first step is always a plain abdominal radiograph. The classic finding is a massively dilated loop of sigmoid colon that rises out of the pelvis and extends toward the diaphragm, forming the "coffee bean sign" (also described as a "bent inner tube" or inverted U-shape). The walls of the distended loop converge toward the left lower quadrant at the point of torsion. If the X-ray is classic and the patient has no signs of peritonitis, you proceed directly to endoscopic decompression (which is both diagnostic and therapeutic). If the X-ray is equivocal, a water-soluble contrast enema will show a "bird's beak" sign, where the contrast column tapers to a point at the site of the twist. CT scan can also confirm the diagnosis and will show the "whirl sign" (twisting of the mesentery and vessels), and it is increasingly used in practice.

For cecal volvulus, plain films may show a markedly dilated, gas-filled cecum that is displaced from the right lower quadrant to the left upper quadrant or midline. There is often an associated small bowel obstruction pattern because the ileocecal valve becomes obstructed. CT abdomen/pelvis is the confirmatory study and will show the "whirl sign" at the point of cecal torsion, along with mesenteric vessel engorgement. An important point: contrast enema and colonoscopic decompression are NOT appropriate for cecal volvulus because they are ineffective and delay surgery.

For neonatal midgut volvulus, the initial abdominal X-ray may show a "double bubble" sign (dilated stomach and proximal duodenum) with a paucity of distal bowel gas, but this finding is nondiagnostic and can overlap with duodenal atresia. The confirmatory test is an upper GI series using water-soluble contrast. The hallmark is the "corkscrew" or "spiral" pattern of the distal duodenum, indicating the midgut is twisted around the SMA axis. Another finding is that the duodenojejunal junction (ligament of Treitz) fails to cross the midline to the left, confirming malrotation. This study must be done urgently, and if midgut volvulus is confirmed (or strongly suspected clinically), the patient goes to the operating room immediately without delay for further imaging.

Critical exam point: In a neonate with bilious vomiting, midgut volvulus is a surgical emergency until proven otherwise. Do not waste time with ultrasound or CT as the primary diagnostic study. The correct next step is an upper GI series, not a lower GI study.

04Management and Treatment

Detailed Management

Sigmoid volvulus without peritonitis: After initial stabilization (IV fluids, electrolyte correction, nothing by mouth, nasogastric decompression), the first therapeutic intervention is flexible sigmoidoscopy. During the procedure, the scope is advanced to the point of torsion. When the twist is reached and reduced, there is usually a dramatic rush of gas and liquid stool, and the bowel decompresses. A rectal tube is left in place for 24 to 48 hours to maintain decompression and allow the bowel wall to recover. Following successful endoscopic decompression, patients should undergo elective sigmoid resection (sigmoidectomy) during the same admission because recurrence rates without definitive surgery are extremely high (reported at 40 to 60 percent or more). Elective resection on a decompressed, prepared bowel allows for a primary anastomosis, avoiding the need for a stoma.

Sigmoid volvulus with peritonitis or nonviable bowel: If there are any signs of peritoneal irritation, hemodynamic instability suggestive of sepsis, or if endoscopic decompression fails or reveals gangrenous mucosa, the patient requires emergent exploratory laparotomy. The gangrenous sigmoid is resected. Because anastomosis on unprepared, ischemic bowel in a septic patient carries a high leak rate, the standard approach is a Hartmann procedure: the proximal bowel is brought out as an end colostomy, and the distal rectal stump is stapled closed. Colostomy reversal can be considered months later when the patient has recovered.

Cecal volvulus: This is a surgical disease from the start. Unlike sigmoid volvulus, endoscopic decompression does not work for cecal volvulus because the anatomy does not allow reliable scope access to the site of torsion. The treatment is emergent right hemicolectomy (resection of the cecum, ascending colon, and terminal ileum with primary ileocolonic anastomosis). Cecopexy (fixing the cecum to the abdominal wall without resection) is an alternative but carries a higher recurrence rate and is generally reserved for patients who are poor surgical candidates.

Neonatal midgut volvulus (Ladd procedure): Once midgut volvulus is diagnosed or strongly suspected, the neonate is taken to the operating room as an emergency. The Ladd procedure involves:

1. Detorsion (counterclockwise rotation to untwist the midgut).

2. Division of Ladd bands (the fibrous bands compressing the duodenum).

3. Broadening the mesenteric base by placing the small bowel on the right side and the colon on the left (non-rotation position).

4. Appendectomy (because the cecum will be in an abnormal position, making future diagnosis of appendicitis unreliable).

Any frankly necrotic bowel is resected. If bowel viability is questionable, a "second look" laparotomy at 24 to 48 hours is performed to reassess before committing to extensive resection, because preserving bowel length is critical to avoiding short bowel syndrome.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The single most tested "gotcha" involving volvulus on licensing exams centers on neonatal bilious vomiting. When a vignette describes a newborn with green or bile-stained emesis, students frequently gravitate toward more common neonatal diagnoses such as duodenal atresia, NEC, or even pyloric stenosis. The trap is failing to recognize that bilious vomiting in a neonate is midgut volvulus until proven otherwise, and the correct next step is an upper GI series (not an ultrasound, not a lower GI study, and not a CT scan). Delay in recognizing this diagnosis results in total midgut infarction and death or lifelong short bowel syndrome, which is precisely why exam writers test it repeatedly. Remember: pyloric stenosis causes non-bilious vomiting and should never be confused with volvulus.

For sigmoid volvulus, the classic error is jumping straight to surgery. In a stable patient without signs of peritonitis, the correct first step is endoscopic decompression (flexible sigmoidoscopy with rectal tube placement), not laparotomy. Surgery is reserved for failure of endoscopic reduction, evidence of bowel necrosis, or peritonitis. Conversely, students must remember that successful endoscopic decompression is not the end of the story: elective sigmoidectomy should follow, because recurrence without surgery is the rule, not the exception.

For cecal volvulus, the trap works in reverse: students may try to apply the sigmoid algorithm (endoscopic decompression first). Colonoscopic decompression does not work for cecal volvulus. The answer is always surgery (right hemicolectomy).

Finally, be attentive to the vignette details that distinguish volvulus from its look-alikes. A "coffee bean sign" on X-ray is sigmoid volvulus. A dilated cecum in the left upper quadrant is cecal volvulus. A "corkscrew" duodenum on upper GI is midgut volvulus. Pneumatosis intestinalis is NEC, not volvulus. These radiographic discriminators are the fastest route to the right answer on the exam.