The ISUOG Clinical Standards Committee, based on the latest evidence, has released practice guidelines that provide recommendations regarding the role of ultrasound in screening for and follow-up of preeclampsia. Preventative strategies (such as low-dose aspirin) for preeclampsia are effective if started in the first trimester and should begin as soon as high-risk status is identified. <\/p>\n\n\n\n
Given the superiority of combined screening, the use of Doppler cut-offs as a standalone screening modality should be avoided if combined screening is available (GRADE OF RECOMMENDATION: B)<\/strong><\/p><\/blockquote>\n\n\n\n
Note: <\/strong>Screening <\/em>refers to identification of at risk cases that may lead to prevention | Prediction <\/em>refers to ability to identify at risk cases, but no evidence available regarding improved outcomes <\/p>\n\n\n\n
Combined Screening<\/a>
Ultrasound Only<\/a>
Multifetal Pregnancies<\/a><\/p>\n\n\n\nKEY POINTS:<\/h2>\n\n\n\n
Combined Screening (10-13 weeks) \u2013 Preferred where available <\/h3>\n\n\n\n
- ASPRE trial results with a 10% FPR (see ASPRE summary in \u2018Related ObG Topics\u2019 below)
- 100% detection rate for preeclampsia <32 weeks <\/li>
- 75% detection rate for preeclampsia <37 weeks <\/li>
- 43% detection rate for preeclampsia \u226537 weeks <\/li><\/ul><\/li><\/ul>\n\n\n\n
Combined screening approach is preferred over ultrasound alone and includes the following (see summary of ASPRE algorithm details in ‘Related ObG Topics’ below) <\/em> <\/p>\n\n\n\n
- Maternal factors
- History | Demographics | CVD and metabolic profile <\/li><\/ul><\/li>
- Maternal arterial BP<\/li>
- Placental growth factor (PlGF) <\/li>
- Pulsatility index (PI) should be used to assess uterine artery resistance
- Transabdominal approach preferred as used for most studies <\/li>
- Transabdominal: Use color flow mapping on a mid-sagittal view of the uterus at the level of the cervical internal os (transabdominal approach) <\/li>
- Transvaginal: Also obtain mid-sagittal view of the uterus, with lateral movement until paracervical vascular plexus is seen and uterine artery is also at the level of the internal cervical os <\/li>
- Identify an ascending or descending branch of the uterine arteries
- Narrow Doppler sampling gate (2 mm) <\/li>
- Insonation angle <30 degrees <\/li>
- Peak systolic velocity of a uterine artery should be greater than 60 cm\/s <\/li>
- PI measurement obtained when 3 identical waveforms are captured <\/li><\/ul><\/li>
- 95th percentile uterine artery mean PI (11-13 weeks)
- Transabdominal: 2.35 <\/li>
- Transvaginal 3.10 for CRL up to 65 mm <\/li><\/ul><\/li>
- Uterine artery PI may be affected by
- Ethnicity: African origin has higher PI <\/li>
- Obesity: Decreasing PI with increasing BMI <\/li>
- History of preeclampsia: Increased PI <\/li><\/ul><\/li><\/ul><\/li><\/ul>\n\n\n\n
Note: <\/strong>Placental volume and vascularization indices are not<\/em> recommended | Combined screening in the second trimester compares favorably to first trimester, but aspirin intervention is ineffective if initiated >20 weeks<\/p>\n\n\n\n
Ultrasound Screening Only <\/h3>\n\n\n\n
First<\/em> Trimester Ultrasound Screening <\/em>(10-13 weeks)<\/em> <\/p>\n\n\n\n