Clinical :-

A 3 year male child complained of vague abdominal pain, discomfort and multiple vomiting episodes approximately every three months since 2 years.

 

The child was operated for malrotation in the early postnatal period .

 

Diagnosis :- Mid-gut volvulus

 

Discussion :-

Midgut volvulus is a complication of malrotation in which clockwise twisting of the bowel around the superior mesenteric artery (SMA) axis occurs because of the narrowed mesenteric attachment. Volvulus can result in bowel obstruction, ischemia, or infarction but is not defined by the presence of or absence of obstruction or ischemia.

 

Congenital malrotation of the midgut often presents within the first month of life. The overall incidence of malrotation, however, is unknown because some patients will present years later or remain asymptomatic for life. The radiologist may encounter this important diagnosis in several different clinical settings such as an incidental imaging finding, the cause of acute abdominal symptoms, or a condition associated with abdominal situs abnormalities.

 

Recurrent epsodes of colicky abdominal pain, with vomiting over a period of months or years are typical and may eventually lead to imaging.

 

Bile-stained emesis and occasional bloody stools are the main presenting clinical indicators and require a rapid imaging investigation

 

In the neonatal period the normal mesentery has a broad base, which extends from the left upper quadrant at the duodenojejunal junction (ligament of Treitz) to the cecum in the right lower quadrant. Midgut malrotation refers to a spectrum of congenital intestinal anomalies of position resulting from a non-rotation or an incomplete counterclockwise rotation of the primitive intestinal loop around the axis of the SMA during fetal development. The failure to complete rotation results in a narrow base of the mesentery, which can predispose the neonate to Volvulus of the midgut (the subsequent twisting of the bowel around the SMA)

 

The direction of the volvulus should be clockwise, since Shimanuki et al noted a counterclockwise whirlpool in patients with enteritis.

 

Ultrasound findings

Should exclude hypertrophic pyloric stenosis and then the relationship between the SMA and SMV should be assessed. In normal population, the SMV is to the right of SMA. The SMA is smaller, round and surrounded by fat, however the SMV is larger and has a thinner wall. In malrotation/volvuls the SMV is to the left of the SMA.

 

Whirlpool sign consists of a side-by-side arrangement of vessels with opposing flow directions, indicating that the whirlpool contains not only the SMV and its tributaries but also branches of the SMA.

 

Fetology

During fetal life, the duodenojejunal and ileocolic portions of the bowel normally rotate counterclockwise 270 degrees around the SMA resulting in the ileocolic valve being located in the right lower quadrant and the ligament of Treitz located in the left upper quadrant. In patients with malrotation, there is typically a narrowed mesenteric pedicle resulting in abnormal position of the ligament of Treitz (which is low lying, to the right of midline, and/or anteriorly located).

 

Associated anomalies are seen in approximately 60% of patients and include congenital heart disease with heterotaxy (abnormal positioning and arrangement of the abdominal organs, such as the spleen, liver, and major blood vessels; right-sided or left-sided isomerism). Malrotation is almost always present in patients with congenital diaphragmatic hernia and abdominal wall defects, such as omphalocele and gastroschisis. Also, malrotation is more common with imperforate anus, duodenal atresia, duodenal web, stenosis, pre-duodenal portal vein, annular pancreas, and biliary atresia.

 

Surgical (Ladd procedure) - The volvulus has to be reduced, and the nonviable bowel to be resected. Transection of Ladd bands is done and the base of the mesentery is surgically broadened.

 

Fetal midgut volvulus

Fetal midgut Volvulus has a specific clinico-echographic presentation. The main complaint of the pregnant woman is the absence of fetal movement. Non-stress-test can show different stages of fetal distress. The ultrasound examination usually gives the diagnosis by the typical image of whirlpool or snail configuration, without peristalsis, and placed centrally in the abdomen. The absence of blood flow by doppler exploration in the centre of the mass suggests gut ischemia. Intestinal necrosis and blood sequestration can be diagnosed by the search for fetal anemia in the observation of non-stress-test and confirmed by the exploration of doppler velocity in middle cerebral artery. Middle cerebral artery showing an increased systolic velocity may help to suspect a fetal anemia related to blood sequestration in necrosed bowel loops. Polyhydramnios is a classical sonographic sign of obstruction. The timing of delivery depends of fetal lung maturity, fetal distress and ultrasound appearance of the fetal gut. Delivery must take place in a tertiary center because immediate surgical correction of this anomaly is indispensable.

 

In summary, the whirlpool sign is an indicator of midgut volvulus on transverse US studies and enables the imaging diagnosis.

Satellite image of a whirlpool. (Image courtesy of NASA Landsat Project Science Office and U.S. Geological Survey Earth Observing System Data Center.)

 

Acknowledgment: I am grateful to Dr.Anirudh Badade for his invaluable guidance and role as mentor

References

1. Pracros JP, Sann L, Genin G, et al. Ultrasound diagnosis of midgut volvulus: the "whirlpool" sign. Pediatr Radiol 1992;22:18-20.

2. Berdon WE. The diagnosis of malrotation and volvulus in the older child and adult: a trap for radiologists. Pediatr Radiol 1995;25:101-103.

3. Shimanuki Y, Aihara T, Takano H, et al. Clockwise whirlpool sign at color Doppler US: an objective and definite sign of midgut volvulus. Radiology 1996;199:261-264. reference

4. Buonomo C, Taylor GA, Share JC Kirks DT. Gastrointestinal Tract. In: Kirks DR, Griscom NT, eds. Practical pediatric imaging. Philadelphia, Pa: Lippincott-Raven, 1998; 857-865.

5. Bernstein SM, Russ PD. Midgut volvulus: a rare cause of acute abdomen in an adult patient. AJR Am J Roentgenol 1998;171:639-641.

6. Berdon WE. Midgut volvulus with whirlpool signs [letter]. AJR Am J Roentgenol 1999; 172:1689-1690.

7. Patino MO, Munden MM. Utility of the sonographic whirlpool sign in diagnosing midgut volvulus in patients with atypical clinical presentations. J Ultrasound Med 2004;23:397-401.

8. front malrotation without volvulus (studyblue.com)

9. medscape.com