What is MMIHS?

Megacystis Microcolon Intestinal Hypoperistalsis Syndrome (MMIHS, Berdon Syndrome) was first described by Walter Berdon in 1976.
It is an extremely rare disorder that affects the bladder and gastrointestinal system. Kidney complications(secondary to bladder complications) are also
extremely common. Most patients diagnosed with MMIHS present all or some of the following indicators: a large, unobstructed bladder, difficulty
or inability to void urine, a small colon, intestinal malrotation, and/or abnormally sluggish intestinal motility with limited or absent ability to absorb nutrients.

Prenatal Diagnosis

MMIHS is typically diagnosed prenatally or more commonly, shortly after birth. The leading indication of MMIHS in utero as seen in fetal ultrasounds is an enlarged bladder (megacystis). The second leading indicator is bilaterally enlarged kidneys (hydronephrosis). In male patients, undescended testicles may be an additional marker.

Polyhydraminos, or increased amniotic fluid in late pregnancy, can also be a strong indicator of MMIHS in utero as it is the main symptom that separates MMIHS from a bladder obstruction. Although some babies with MMIHS are born naturally and at full term, Polyhydraminos or other complications can put them at risk for a preterm delivery. 

A doctor who suspects a diagnosis of MMIHS in utero may also test for colon activity in the third trimester and see significantly decreased or absent activity.

Postnatal Diagnosis

Post birth indicators may include a distended abdomen, enlarged bladder and kidneys as evident on neonatal ultrasound, bile stained vomiting, and failure to pass meconium.

In addition to a bladder obstruction, early diagnosis of MMIHS can also be mistaken for Hirschsprung’s disease. However, analysis of a colonic biopsy will show the presence of ganglion cells (which are not present in Hirschsprung’s patients), and in some cases, an abundance of these cells. 

Genetics

Although inherited genetic mutations have been reported, a majority of the information that is available states that most patients with MMIHS show an alteration of a gene that is present for the first time in one family member (de novo). Reports also show that MMIHS seems to be more prevalent in females.

As unique as the syndrome is, so are it’s patients.  Although the symptoms are usually similar, the severity of the syndrome can be different for each patient and can even fluctuate amongst the patients themselves. Education and awareness of MMIHS is critical as proper diagnosis and treatment can significantly impact the prognosis for each individual.

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