Case 1

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 firm and 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 shows an obvious bowel obstruction. A surgeon performs a laparotomy which finds extensive small bowel necrosis 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, vasoactive 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 alone.

Case 2

A 4 month old female presents with 9 episodes vomiting which were initially yellow, but the last 4 have been green. There is no diarrhea. She last passed a stool two days ago. She has a history of poor weight gain and an illness 3 weeks ago with vomiting that resolved. She is feeding a partially hydrolyzed formula because of colic.

Exam VS T37, HR 160, RR 35, BP 110/60. She is crying and arches her back at times. Her anterior fontanelle is flat and soft. Her eyes are slightly sunken. There are no tears with crying. Her oral mucosa is sticky. Heart is tachycardic with no murmur. Lungs are clear. Abdomen is firm, difficult to palpate, hypoactive bowel sounds. No inguinal hernias. Normal female external genitalia. Skin turgor is good. Color is slightly pale. Capillary refill time is 3 to 4 seconds.

A midgut volvulus is clinically suspected. Blood is drawn for laboratory studies. An IV fluid NS infusion is initiated. A stat upper GI series is ordered and a surgeon is alerted to the possibility of a midgut volvulus. The initial abdominal X-ray shows a dilated stomach and a paucity of bowel gas elsewhere (Figure 1). The upper GI series shows sluggish contrast flow in a corkscrew fashion as it exits the stomach (Figure 2) confirming a midgut volvulus. The patient is taken to surgery where the midgut volvulus is detorsed and a Ladd procedure is performed.

Figure 1. The stomach is dilated and there is a paucity of gas distal to this. Copyright 1995 Loren Yamamoto. Taken from Yamamoto LG. Bilious Vomiting in a 3-Month Old. In: Yamamoto LG, Inaba AS, DiMauro RM (eds). Radiology Cases in Pediatric Emergency Medicine, 1995.
www.hawaii.edu/medicine/pediatrics/pemxray/v3c17.html Accessed September 2022.

Figure 2. After thin barium oral contrast is given via nasogastric tube, the stomach fills with contrast. The contrast exits the stomach slowly in a corkscrew fashion (black arrow) indicative of a midgut volvulus. Copyright 1995, Loren Yamamoto. Taken from Yamamoto LG. Bilious Vomiting in a 3-Month Old. In: Yamamoto LG, Inaba AS, DiMauro RM (eds). Radiology Cases in Pediatric Emergency Medicine, 1995.
www.hawaii.edu/medicine/pediatrics/pemxray/v3c17.htmlAccessed September 2022.

Malrotation of the intestines refers to an anatomic abnormality in which the intestines are suspended from the peritoneum by a relatively narrow stalk (Figure 3-right image) rather than the normal broad attachment (Figure 3-left image). Comparing malrotation and the normal anatomy, you can see that it is anatomically impossible for the small bowel to twist on the wide attachment in the normal anatomy (Figure 3-left image), while it is relatively easy for the small bowel to twist on the relatively narrow attachment in the malrotation malformation (Figure 3-right image). This narrow attachment is easily susceptible to twisting resulting in a midgut volvulus causing ischemia to a large portion of the small bowel (Figure 4) (1). Note that in figure 4, nearly the entire small bowel is ischemic since it is distal to the twist such that if this midgut volvulus is not detorsed soon, infarction and necrosis of the entire small bowel will result.

Figure 3. This schematic diagram shows the broad peritoneal attachment of the small bowel normal anatomy on the left and the narrow stalk-like peritoneal attachment of the small bowel in the malrotation malformation making it prone to twisting (arrow)

Figure 4. This schematic diagram shows a twisting of the peritoneal attachment (arrow) resulting in ischemia of the entire small bowel.

The majority of children with malrotation present with midgut volvulus within the first year of life; however new research has shown that malrotation is present in older adolescents and adults at higher rates than previously thought (2). The presence of other malformations such as diaphragmatic hernia, congenital heart defect, or omphalocele are highly associated with intestinal malformation and thus should be considered even in asymptomatic patients presenting with other malformations especially heterotaxy syndrome (also called isomerism is a rare condition in which there anomalies of the heart, lung, and other organs) (3,4).

During the 4th to 8th week of normal embryological development, the developing intestines herniate out of the abdominal cavity through the umbilicus while simultaneously undergoing 90 degrees of counterclockwise rotation. As the intestines return into the peritoneum during the 8th to 10th week they undergo an additional 180 degrees of rotation with the final result being a total of 270 degrees of counterclockwise rotation and a broad fan of mesentery (5). This creates the characteristic C-shape of the duodenum as the jejunum and ileum are centrally located within the peritoneum as it travels from the left upper quadrant and terminates at the ileocecal junction in the right lower quadrant.

Intestinal malformation results from the incomplete rotation of the duodenojejunal limb and only partial rotation of the cecocolic limb (5,6). This results in a stalk of bowel and mesentery that can twist on itself. Additionally, the formation of Ladd’s bands, fibrous bands of peritoneum that attach the cecum to the peritoneal wall, can form over the duodenum and cause external compression and obstruction (6). Nonrotation is a variant of malformation in which the small bowel remains on the right side of the abdomen and the cecum lies on the left or midline of the lower abdomen; however, Ladd’s bands do not form thus the cecum is more mobile and the mesentery is not as narrowed, resulting in lower risk of midgut volvulus or duodenal compression (7).

When the intestines twist around its malrotation stalk this creates a surgical emergency known as midgut volvulus (Figure 4). The torsion of this stalk creates a small bowel obstruction and ischemia to nearly the entire length of the small intestine which must be immediately corrected or the entire section of intestine can infarct and necrose. This will present as bilious vomiting. There is likely acute abdominal pain as well, but this can be difficult to confirm in neonates. Bilious vomiting in a neonate or infant is a potential midgut volvulus time-sensitive surgical emergency until proven otherwise. Significant morbidity and mortality occurs if the diagnosis and surgical intervention are delayed (7). It has been observed that older children tend to present atypically, with less severe symptoms such as nonbilious vomiting and vague recurrent abdominal pain (8). Another complication can arise if the Ladd bands compress the duodenum causing a small bowel obstruction.

Recurrent volvulus, also known as intermittent volvulus, occurs if the intestines twist and untwist spontaneously leading to temporary relief of symptoms. Upon initial twisting, it logically follows that the bowel could untwist or twist tighter. The former is an intermittent volvulus while the latter is an acute emergency midgut volvulus. This can complicate the diagnosis; however acute abdominal pain and bilious vomiting in any child should warrant emergent investigation (9). Intermittent volvulus should be suspected in patients with a history of more than one episode of severe vomiting that suddenly abates. Note that in case 1, there were clues to the possibility of an intermittent midgut volvulus. If the intermittent volvulus was suspected and an upper GI series was obtained prior to his acute presentation, the malrotation would have been identified and surgical correction could have been performed to prevent his subsequent delayed presentation with the acute midgut volvulus and resulting bowel infarction. Also note that case 2 describes an infant with a history of infant colic, which could have been caused by a mild intermittent volvulus.

Severely ill and unstable patients should be resuscitated and immediately evaluated by a surgeon for emergency laparotomy. Moderately ill patients should have a stat upper GI series to confirm or rule out midgut volvulus and malrotation. Confirmatory findings include a beak sign in which the contrast abruptly stops in the duodenum or a corkscrew contrast pattern (figure 2 in the case) which is caused by the twisting of the duodenum within the midgut volvulus. Given the ever expanding indications for ultrasound, some have advocated the use of ultrasound which has high sensitivity and specificity in diagnosing malrotation with midgut volvulus (10). A whirlpool sign on Doppler ultrasonography can identify the twisting of the SMA (superior mesenteric axis) and has high diagnostic value. However, a negative or inconclusive ultrasound study is not sufficient for ruling out malrotation and thus if clinical suspicion remains, these patients should undergo an upper GI series. Performing an indeterminate ultrasound can delay the time to surgery for a potential midgut volvulus diagnosis which is very time sensitive. The upper GI series remains the gold standard of diagnosis for malrotation with or without midgut volvulus as it can be used to diagnose malrotation even in asymptomatic patients, such as in a stable patient with intermittent volvulus. The presence of a displaced duodenal-jejunal junction can diagnose malrotation even if a midgut volvulus is not present at the time (11).

Once a midgut volvulus is confirmed, an open surgical approach is often employed to manually detorse the small bowel to restore circulation and prevent ischemic necrosis. The definitive surgical procedure is known as a Ladd procedure in which the surgeon divides the Ladd bands, broadens the mesentery, and places the small bowel on the right side and the cecum on the left side (reverse of the normal anatomy) which minimizes the chance of midgut volvulus. Adhesions from the peritoneum can also further reduce the chance of recurrent midgut volvulus (3).

A Ladd procedure can also be done laparoscopically for non-acute cases but there should be a low threshold to convert to an open surgical procedure in the event of complications such as midgut volvulus, intestinal dilation, and/or chylothorax to improve access and mobility for the surgeon. Additionally, while the less invasive laparoscopic approach has demonstrated faster recovery times and comparable post-op complication rates, there have been significantly higher rates of recurrent midgut volvulus associated with the laparoscopic approach (12). It is suggested that these higher rates of recurrent volvulus might be due to fewer adhesions formed in minimally invasive surgery which allows more mobility of the cecum and small intestines to re-torse.

Complications following surgical correction of malrotation and midgut volvulus include recurrent midgut volvulus, small bowel adhesions, and short gut syndrome. Recurrent midgut volvulus, occurring in up to 10% of cases, is thought to occur due to insufficient widening of the mesentery or lack of adhesion fixation of the newly mobilized bowel. Regardless of etiology, recurrent midgut volvulus requires additional surgical correction to prevent bowel ischemia and infarction (13). The lifetime risk of small bowel adhesions resulting in small bowel obstruction ranges from 5.6% to 24% of cases (13,14). Overall, the morbidity and mortality following a Ladd procedure to correct intestinal malformation is under 10% and rates of total resolution of symptoms are near 90% making the identification and management of intestinal malformation critical.

In communicating with surgeons, use the term "midgut volvulus" since this is very clear. It communicates a serious diagnosis requiring immediate attention. The term volvulus by itself is less clear since it communicates a variety of conditions, some of which do not require surgery.

Related x-rays
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

Questions
1. What are the two mechanisms of a bowel obstruction associated with malrotation?

2. Is the term "malrotation" useful to understand the acute pathogenesis of a midgut volvulus?

3. What is the most reliable imaging procedure to identify or rule out a malrotation in the absence of a midgut volvulus?

4. Which alternate name for "malrotation" better describes the pathogenesis of how a midgut volvulus occurs in a patient with a malrotation?
   a. mesenteric axis inversus
   b. guts on a stalk
   c. Ladd’s bands syndrome
   d. non-rotation

5. Is it likely that one could have a malrotation and never have a volvulus throughout life?

6. In case 2, the history of infant "colic" could be due to which alternative diagnostic etiology?
   a. urinary tract infection
   b. occult omphalocele
   c. intussusception
   d. intermittent volvulus

References
1. Kimura K, Loening-Baucke V. Bilious vomiting in the newborn: rapid diagnosis of intestinal obstruction. Am Fam Physician. 2000 May 1;61(9):2791-8.
2. Aboagye J, Goldstein SD, Salazar JH, et al. Age at presentation of common pediatric surgical conditions: Reexamining dogma. J Pediatr Surg. 2014;49(6):995-999. doi:10.1016/j.jpedsurg.2014.01.039
3. Bonasso P. Chapter 81. Malrotation. In: Holcomb GW, Murphy JP, St.Peter SD (eds). Holcomb and Ashcraft’s Pediatric Surgery, Seventh Edition. 2019. Elsevier, St. Louis. pp: 507-516.
4. Graziano K, Islam S, Dasgupta R, et al. Asymptomatic malrotation: Diagnosis and surgical management: An American Pediatric Surgical Association outcomes and evidence based practice committee systematic review. J Pediatr Surg. 2015;50(10):1783-1790. doi:10.1016/j.jpedsurg.2015.06.019
5. Chung DH. Chapter 67. Pediatric Surgery. In: Townsend CM (ed). Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice, 21st edition. 2022 Elsevier, St Louis. pp: 1844-1882
6. Dassinger MS, Smith SD. Chapter 86. Disorders of Intestinal Rotation and Fixation. In: Coran AG, Caldamone A, Adzick NS, Krummel TM, Laberge JM, Shamberger R (eds). Pediatric Surgery, Seventh Edition. 2012. Saunders, Philadelphia pp: 1111-1125
7. Stockman PT. Chapter 81. Malrotation. In: Oldham KT, Brown B, LaPlante MM, Adkins ES (eds). Principles and Practice of Pediatric Surgery, Second edition. 2005. Lippincott Williams & Wilkins, Philadelphia.
8. Powell DM, Biemann OH, Smith C. Malrotation of the intestines in children: The effect of age on presentation and therapy. J Pediatr Surg. 1989;24(8):777-780. doi:10.1016/S0022-3468(89)80535-4
9. Mohinuddin S, Sakhuja P, Bermundo B, Ratnavel N, Kempley S, Ward HC, Sinha A. Outcomes of full-term infants with bilious vomiting: observational study of a retrieved cohort. Arch Dis Child. 2015;100(1):14-17. doi: 10.1136/archdischild-2013-305724.
10. Zhang W, Sun H, Luo F. The efficiency of sonography in diagnosing volvulus in neonates with suspected intestinal malrotation. Medicine. 2017;;96(42):e8287. doi: 10.1097/MD.0000000000008287.
11. Tackett JJ, Muise ED, Cowles RA. Malrotation: Current strategies navigating the radiologic diagnosis of a surgical emergency. World J Radiol. 2014;6(9):730-736. doi: 10.4329/wjr.v6.i9.730.
12. Scalabre A, Duquesne I, Deheppe J, Rossignol G, Irtan S, et al. Outcomes of laparoscopic and open surgical treatment of intestinal malrotation in children. J Pediatr Surg. 2020;55(12):2777-2782. doi:10.1016/j.jpedsurg.2020.08.014.
13. Aidlen J. Chapter 2. Malrotation. In: Dolgin SE, Hamner CE (eds). Surgical Care of Major Newborn Malformations. 2012. World Scientific, Singapore. pp: 33-56.
14. El-Gohary Y, Alagtal M, Gillick J. Long-term complications following operative intervention for intestinal malrotation: a 10-year review. Pediatr Surg Int. 2009;26(2):203-206. doi:10.1007/s00383-009-2483-y

Answers to questions
1. a) Ladd's bands compressing and obstructing the proximal small bowel. b) Midgut volvulus.
2. The term "malrotation" originates from its embryological etiology which is of little value in its acute presentation. It potentially distracts from the understanding of why the midgut volvulus occurs in this malformation.
3. Upper GI series. Barium enema and ultrasound are less reliable.
4. b. Guts on a stalk best describes why the midgut volvulus occurs. In the normal anatomic configuration, the small bowel is suspended by mesentery that has a broad attachment making it nearly impossible to twist, while in a malrotation, the small bowel is suspended by narrow mesentery that is stalk-like and is prone to twisting.
5. Yes. The number of patients with a malrotation who never develop a midgut volvulus is uncertain, but more recent estimates of this are higher than estimates in the past.
6. d. intermittent volvulus. This infant could have had intermittent volvulus as the cause of fussy episodes which were felt to be due to infant "colic".