Diagnosing VTS

Some of the diagnostic terms that may be used to define cases of vanishing twin syndrome during pregancy:

1) Blighted ovum

2) Intrauterine fetal demise (IUFD)

3) Fetus papyraceous 

4) Missed miscarriage

5) Complete miscarriage

While the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) has guidelines for identifying a blighted ovum, fetus papyraceous, and other outcomes of miscarriages of multiples, no official guidelines currently exist for diagnosing the occurrence of VTS. Instead, VTS is informally identified by a medical professional via the absence, death, cessation of development of one or more multiples (i.e., twins, triplets, or higher-order) at any point in pregnancy following their confirmed presence in one or more prior ultrasounds.

Symptoms of VTS and many other forms of miscarriage may include, but are not limited to:

• Vaginal bleeding

• Cramping

• Placental abruption

• Intrauterine growth restriction (IUGR)

• Hypertension

• Premature rupture of membranes (PROM)

• Cervical insufficiency 

• Fetal malformations, such as spina bifida

• Low  birth weight

• Low Apgar scores

• Placental pathologies, such as small placentas and infarcts

• Preterm labor

• Long-term psychological impacts on pregnant individuals and surviving children

• Chimerism in surviving children

• Epigenetic effects, such as changes in methylation in surviving children

Vanishing twin syndrome (VTS) occurs when one embryo or fetus in a multiple pregnancy stops developing and is gradually reabsorbed or compressed in the uterus. The remaining baby (or babies) usually continue to grow normally. While VTS is often recognized during pregnancy by ultrasound, some cases are discovered only after delivery — this is called a postpartum diagnosis. Whether discovered during pregnancy or after birth, vanishing twin syndrome reflects a real twin relationship and a real loss. Documenting that history can help support medical understanding, aid in emotional healing when and where it may be needed by families and surviving multiples, and promote evidence-based and patient-centered care.

How VTS May Be Identified After Birth

1. Placental Findings

A pathologist may note evidence of a twin/multiple pregnancy such as:

• The presence of an additional gestational sac(s)

• A compressed fetus (fetus papyraceus)

• Extra membranes or vessel patterns

• These findings can appear during placental examination following a singleton birth.
  
  

2. Review of Prenatal Records

• Early ultrasounds may have shown two sacs or embryos even if later scans appeared singleton.

• Sometimes this information isn’t revisited until after delivery.
  
  

3. Genetic or Laboratory Clues

• Cell-free DNA (cfDNA/NIPT) or newborn genetic results may show unexpected DNA fragments from a vanished co-twin.

• This is sometimes called a “vanishing twin effect” in genetic testing.
  
  

4. Neonatal or Pathologic Clues

• Differences in the placenta, cord, or newborn circulation (such as anemia-polycythemia features or growth restriction) can suggest prior twin sharing of blood supply.
  
  

Why It Matters

Medical Perspective

• Twin/multiple gestation is associated with unique developmental and hematologic risks.

• Recording twin status in the medical file of the surviving multiple(s) helps guide growth tracking, imaging review, and potential follow-up testing.

• Pathology findings also help explain complications such as bleeding, abnormal hormone patterns, or growth differences.
  
  

Emotional and Family Perspective

• Parents may feel surprise, confusion, or grief upon learning of a vanished twin after birth.

• Recognizing this as a real and valid loss can be important for emotional healing.

• Hospitals should offer access to perinatal bereavement or counseling services, and families may connect with peer networks.
  
  

Next Steps for Families

1. Ask for written explanations of placental or genetic findings from your care team.

2. Request that “twin/multiple pregnancy” be documented in your medical record, even if one baby survived.

3. Seek support—you may grieve both the baby(-ies) who died and the complexity of the pregnancy.

4. Monitor the surviving baby’s development through routine pediatric follow-up.
   
   

Global Variations

• In the U.S., postpartum VTS may appear in obstetric or pathology reports but rarely on birth certificates.

• The U.K. and some European and Australian health systems often document VTS findings in maternity records and placental pathology reports.

• In regions with limited imaging or pathology access, VTS may remain undiagnosed but can still influence pregnancy outcomes.

• No matter the system, the experience is valid, and the surviving multiple's(s') twin status is important to document.