Pregnancy of uncertain viability
Pregnancy of uncertain viability (PUV) is a term given to an intrauterine pregnancy in a situation where there are not enough criteria (usually on ultrasound grounds) to confidently categorise an intrauterine pregnancy as either viable, or a failed pregnancy.
Various authors have put forward definitions for a pregnancy to be categorised under this group (please refer to your local protocol/guidelines). Endovaginal/transvaginal ultrasound will show 1-3:
- intrauterine gestational sac containing an embryo with CRL <7 mm with no fetal cardiac activity
- gestational sac with MSD <25 mm containing no embryo
Treatment and prognosis
It is important that pregnancy failure is confirmed with absolute certainty, even in situations where it is thought highly likely, but does not meet the established criteria.
Recommendations for the most appropriate followup of a pregnancy of uncertain viability are evolving. In a recent BMJ publication4, the authors suggest the following:
- if MSD < 12mm with no embryo
- rescan in 14 days.
- if MSD has not doubled and there is still no embryo - diagnosis of failed pregnancy can be made.
- if MSD 12 - 25 mm with no embryo
- rescan in 7 days
- if no embryo with cardiac activity present - diagnosis of failed pregnancy can be made.
- if CRL <7mm no heart beat
- rescan in 7 days
- if still no hearbeat with any size CRL - diagnosis of failed pregnancy can be made.
Although radiologists commonly use "viable" loosely in the first trimester to mean "living," in some settings, the term "viability" has a specific legal definition (see: failed pregnancy).
- 1. Bignardi T, Condous G, Kirk E et-al. Viability of intrauterine pregnancy in women with pregnancy of unknown location: prediction using human chorionic gonadotropin ratio vs. progesterone. Ultrasound Obstet Gynecol. 2010;35 (6): 656-61. Ultrasound Obstet Gynecol (full text) - doi:10.1002/uog.7669 - Pubmed citation
- 2. Bottomley C, Van Belle V, Pexsters A et-al. A model and scoring system to predict outcome of intrauterine pregnancies of uncertain viability. Ultrasound Obstet Gynecol. 2011;37 (5): 588-95. Ultrasound Obstet Gynecol (full text) - doi:10.1002/uog.9007 - Pubmed citation
- 3. Bickhaus J, Perry E, Schust DJ. Re-examining Sonographic Cut-off Values for Diagnosing Early Pregnancy Loss. Gynecol Obstet (Sunnyvale). 2013;3 (01): 141. doi:10.4172/2161-0932.1000141 - Free text at pubmed - Pubmed citation
- 4. Preisler J et al. Defining safe criteria to diagnose miscarriage: prospective observational multicentre study. BMJ (Clinical research ed.). 351: h4579. Pubmed
First trimester of pregnancy
- ultrasound findings in early pregnancy
- confirming intrauterine gestation
- pregnancy of unknown location (PUL)
first trimester vaginal bleeding
- ectopic pregnancy
failed early pregnancy
- pregnancy of uncertain viability (PUV)
- anembryonic pregnancy
- yolk sac abnormalities
- gestational trophoblastic disease
- subchorionic haemorrhage
- demise of a twin
- implantation bleeding
- aneuploidy testing