A 6 year old male is brought to the ED with a chief complaint of abdominal pain and vomiting. He has vomited 15 times since the onset of illness 30 hours ago. He is complaining of diffuse abdominal pain. His mother was attempting to give him small amounts of juice at a time, but this was not succeeding. He feels weak and he looks pale. His urine output is diminished. He was completely normal prior to the onset of vomiting. He has no fever, diarrhea, dysuria or coughing. His past history is significant for two previous episodes of severe abdominal pain associated with about 3 episodes of vomiting which resolved on its own. The first episode occurred at age 3 and the second episode occurred at age 5.
Exam VS T37, HR 100, RR 30, BP 110/70. He is moderately ill appearing; pale and somewhat weak. His eyes are sunken. His oral mucosa is moist. Neck supple. Heart regular. Lungs are clear. Abdomen is soft and mildly tender all over. Bowel sounds are diminished. He has no inguinal hernias and his testes are normal. His back is non-tender. His skin turgor is diminished.
An abdominal series is obtained which shows an obvious bowel obstruction. A surgeon is consulted and at laparotomy, his entire small bowel is found to be necrotic due to a midgut volvulus. The necrotic small bowel requires resection. He is admitted to the ICU post operatively. He develops shock requiring aggressive fluid resuscitation, pressors and inotropes. He eventually survives, but he will require parenteral nutrition for the rest of his life, since he does not have enough small bowel to survive with enteral nutrition.
Malrotation of the intestine refers to an intestinal malformation in which the intestines are suspended by a stalk rather than a broad fan of peritoneum. The term "malrotation" emphasizes the embryology of the malformation. From a clinician's standpoint, it is probably best to forget this since it is merely confusing trivia of little clinical importance.
In malrotation, the intestines function normally, so the patient is entirely asymptomatic until a complication of the malrotation occurs. Malrotation should really be renamed to "guts on a stalk syndrome" because this is the clinical feature that causes the major complication of malrotation in which the peritoneal attachments suspend the intestines like a stalk rather than a broad fan. If the attachment of the intestine to the peritoneum and abdominal wall is normal, it is broad extending from the right lower quadrant, across the back of the abdominal wall toward the left upper portion of the abdomen. This broad attachment (like a rectangular flag) makes it difficult or impossible for the intestinal loops to twist and cause an obstruction. However, in malrotation, the intestines are suspended from a narrow attachment to the back of the abdominal wall, which makes the intestines highly susceptible to twisting about this stalk (guts hanging on a stalk). This is called a midgut volvulus. Once the stalk twists, there is a fair likelihood that it will untwist on its own, relieving the volvulus. However, if this fails to occur, or if it twists the wrong way to make the twist tighter, blood flow to the intestines is interrupted, and this midgut volvulus eventually results in a catastrophic bowel infarction. This is why, this syndrome should be renamed "guts on a stalk syndrome".
Note that the patient in our case example had two previous episodes of vomiting with abdominal pain which resolved on its own. These could have been episodes of "intermittent volvulus" which occurs when the volvulus just happens to twist, then untwist on its own. If the clinician is really smart, it may be possible to diagnose a malrotation just from a history or clinical pattern consistent with an intermittent volvulus. How can a malrotation be diagnosed if the patient does not have a midgut volvulus at the time? An upper GI series will show that the junction of the duodenum and jejunum are misplaced. A barium enema may identify that the cecum is not in the right lower quadrant where it should be, which is indicative of a malrotation; however, this finding is not as reliable as the upper GI series findings. An ultrasound may be able to identify a misplacement of the superior and inferior mesenteric axes coming off the descending aorta which is indicative of a malrotation, but again, this sign is not 100% diagnostic.
Malrotation may also present with a less severe form of a bowel obstruction in which the stalk of the peritoneum known as Ladd's bands, may overlie and compress the underlying bowel causing a bowel obstruction. This does not necessarily occur with a midgut volvulus which is much more serious.
Otherwise, the presentation of a malrotation is with an acute bowel obstruction caused by a midgut volvulus. This diagnosis must be made IMMEDIATELY because only prompt surgical intervention can relieve the volvulus which restores perfusion to the bowel, to prevent a catastrophic bowel infarction. The anatomy of a midgut volvulus is such that the bowel infarction that results is truly catastrophic since it often involves the entire small bowel. This results in substantial tissue necrosis and complications such as shock and sepsis. If the patient is able to survive this, parenteral nutrition is required for the remainder of his/her life since there is not enough bowel remaining for enteral nutrition.
Midgut volvulus should not be confused with sigmoid volvulus which generally occurs in adults. Sigmoid volvulus involves the large bowel and can often be decompressed by barium enema or other non-surgical procedures. In a sigmoid volvulus, the sigmoid is excessively lengthy. It has a tendency to twist upon itself resulting in a sigmoid obstruction. Abdominal radiographs demonstrate a gas distended sigmoid colon. Non-surgical reduction measures are usually successful.
This is opposed to a midgut volvulus, which occurs mostly in children with a malrotation. Approximately half the cases of malrotation will present during the neonatal period with an acute bowel obstruction. However, the other cases can present with an acute bowel obstruction at any time.
1. What are the two mechanisms of a bowel obstruction associated with malrotation?
2. Does the term "malrotation" refer to any patient condition, symptom or malformation description that is relevant for clinicians?
3. What is the most reliable imaging procedure to identify or rule out a malrotation in the absence of a midgut volvulus?
4. Name two different types of intestinal volvulus and describe how they are different.
5. Is it likely that one could have a malrotation and never have a volvulus throughout life?
Malrotation and volvulus: Rosen LM, Yamamoto LG. Abdominal Pain and Vomiting in a 7-Year Old. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1995, volume 2, case 8. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v2c08.html
Midgut volvulus case: Yamamoto LG. Bilious Vomiting in a 3-Month Old. In: Yamamoto LG, Inaba AS, DiMauro R (eds). Radiology Cases In Pediatric Emergency Medicine, 1995, volume 3, case 17. Available online at: www.hawaii.edu/medicine/pediatrics/pemxray/v3c17.html
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6. Imbembo AL, Zucker KA. Volvulus of the colon. In: Sabiston DC (ed). Textbook of Surgery, The Biological Basis of Modern Surgical Practice, 14th edition. Philadelphia, W.B. Saunders Company, 199, pp. 940-944.
7. Smith EI. Malrotation of the intestine. In: Welch KJ, Randolph JG, Ravitch MM, O'Neill JA, Rowe MI (eds). Pediatric Surgery, fourth edition. Chicago, Year Book Medical Publishers, 1986, pp. 882-895.
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Answers to questions
1. a) Ladd's bands compressing and obstructing the proximal small bowel. b) Midgut volvulus.
2. The term "malformation" originates from the embryological formation of the malrotation which is of little or no value for clinicians.
3. Upper GI series. Barium enema and ultrasound are less reliable.
4. Midgut volvulus and sigmoid volvulus. Midgut volvulus is a true surgical emergency involving nearly the entire small bowel which will infarct unless the volvulus is relieved surgically. Sigmoid volvulus, which occurs in the elderly, involves the sigmoid colon and can usually be relieved without surgical means.
5. It is unlikely, but it can happen. About half the patients with a malrotation will present in the neonatal period, with the other half presenting at any other age.