Dear Colleague,  
I met today in consultation Mrs. Angelette BOSSE, born on 09/04/1980, accompanied by her partner, Mr. HOUDE, to discuss the detection of trisomy 18 during the current pregnancy.  

Family history:  
Mrs. BOSSE is in good health. She reports no particular pathologies, disabilities, or cases of IUFD in her family branch. Mr. HOUDE is also in good health.  

History of the pregnancy:  
Spontaneous pregnancy, estimated start date 07/05/2023.  
The first-trimester ultrasound revealed a cystic hygroma with a nuchal translucency measured at 7 mm for a crown-rump length of 55 mm. A trophoblast biopsy was therefore performed. The karyotype from direct examination of the chorionic villi revealed a free and homogeneous trisomy 18. The karyotype from culture is in progress. The follow-up ultrasound showed a mega-bladder and holoprosencephaly.  
I saw the couple at 15 weeks GA.  
We briefly discussed the consequences of trisomy 18 on the health of affected individuals. Trisomy 18 is a severe polymalformative syndrome. More than 95% of affected fetuses die in utero. Live-born children present with hypotonia, hyporeactivity, and sucking difficulties, evolving towards hypertonia with almost no contact. Malformations are common: heart (> 90% of cases), digestive tract (esophageal atresia, anorectal malformation), kidneys and urinary tract (hydronephrosis, unilateral or bilateral agenesis), eyes (microphthalmia, coloboma), etc.  
The couple wishes to proceed with a request for medical termination of pregnancy. I therefore have them sign the request today, which will be discussed at the next MRB meeting.  
The mechanism of free and homogeneous trisomy 18 is accidental, and the recurrence risk for the couple is low, around 1%. This risk only slightly increases with age, unlike the risk of trisomy 21. In this context, systematic NIPT is proposed for subsequent pregnancies. If the NIPT and first-trimester ultrasound are unremarkable, this will be reassuring regarding the absence of recurrence of trisomy 18 in the current pregnancy.  

In summary:  
Free and homogeneous trisomy 18, detected during the current pregnancy (hygroma, malformations, direct karyotype). The couple requests a medical termination of pregnancy.  
I remain at your disposal and that of the couple for any further questions.  
Best regards.