Prenatal Care After a PAS Diagnosis

Introduction

Receiving a Placenta Accreta Spectrum (PAS) diagnosis can feel overwhelming. One of the first questions many patients ask is: "What changes now?"

The good news is that most of your standard prenatal care continues as usual. However, your care will shift to a higher level of monitoring and planning. Some procedures are modified or avoided, and new ones are added to keep you and your baby as safe as possible. This page walks you through exactly what to expect.

What Stays the Same

It can be reassuring to know that many routine parts of prenatal care do not change after a PAS diagnosis. Here are the key tests and practices that continue as normal:

Glucose Tolerance Test (GTT)

The standard glucose screening for gestational diabetes (GDM) at 24–28 weeks is safe to proceed with a PAS diagnosis. The glucose drink does not cause uterine contractions or pose any hemorrhage risk. No major guideline body — including ACOG, SMFM, FIGO, or RCOG — contraindicates the GTT for PAS patients.1

In fact, GDM screening is especially important for PAS patients. Gestational diabetes can lead to macrosomia (a larger-than-average baby), which complicates PAS deliveries by increasing surgical difficulty and blood loss risk.

Transvaginal Ultrasound

Transvaginal ultrasound is not only safe — it is the gold standard for monitoring PAS. The ultrasound probe does not reach the placenta and poses no risk of disruption or bleeding. The SMFM Ultrasound Marker Task Force (2021) specifically endorses transvaginal ultrasound as a key diagnostic and monitoring tool for PAS.5

Standard Vaccinations

All routine pregnancy vaccinations remain safe and recommended:

• Flu shot — safe at any point during pregnancy
• Tdap (tetanus, diphtheria, pertussis) — recommended at 27–36 weeks. Because PAS deliveries often occur at 34–36 weeks, consider getting Tdap early in the recommended window to ensure adequate antibody transfer to your baby.
• COVID-19 vaccine — safe per current guidelines, with no PAS-specific contraindications

Prenatal Vitamins

Continue your standard prenatal vitamin supplementation, including standard-dose folic acid (400–800 mcg/day). There is no need to change your vitamin routine after a PAS diagnosis. However, do not take mega-doses of any supplement without your provider's guidance — more is not always better.

Dental Care

Routine dental cleanings and fillings remain safe during a PAS pregnancy. The second trimester is generally the preferred window for elective dental procedures. Good oral health supports overall health during pregnancy, so do not postpone necessary dental care.

What Changes — Tests and Procedures

While much of your care stays the same, several important changes apply after a PAS diagnosis. Some familiar procedures are modified or avoided entirely.

Digital Cervical Exams — AVOID

Instead of digital exams, your care team should use transvaginal ultrasound to assess cervical length and changes. This provides the same clinical information without the risk of disturbing the placenta. The RCOG Green-top Guideline 27a specifically recommends against digital vaginal examination in the setting of placenta previa and accreta.3

Amniocentesis — AVOID for Lung Maturity

Amniocentesis (inserting a needle through the abdomen to sample amniotic fluid) for the purpose of testing fetal lung maturity should be avoided. The ACOG/SMFM Obstetric Care Consensus #7 explicitly states that amniocentesis for lung maturity is not recommended in PAS because the results would not change the delivery timing — delivery is planned based on gestational age regardless.1

For genetic testing, your provider should offer NIPT (non-invasive prenatal testing using cell-free fetal DNA from a simple blood draw) as the preferred alternative. If amniocentesis is absolutely necessary for genetic reasons, it must be performed under ultrasound guidance with careful avoidance of the placenta.

GBS Screening — Timing Adjusted

Group B Streptococcus (GBS) screening is normally done via a vaginal-rectal swab at 36–38 weeks. The swab itself remains safe for PAS patients. However, the timing often needs adjustment because most PAS patients deliver at 34–36 weeks — before the standard screening window.

In practice, for planned cesarean deliveries without labor or premature rupture of membranes (PROM), GBS prophylaxis (preventive antibiotics) is not routinely needed per ACOG guidelines. Your care team will determine the best approach for your situation.

Delivery Timing — Earlier Than Typical

This earlier delivery window balances two competing risks: the risk of prematurity for the baby versus the risk of emergency hemorrhage for the mother. Your care team will determine the optimal timing based on your specific clinical picture.

Enhanced Monitoring Added

After a PAS diagnosis, your care plan will include several new layers of monitoring that go beyond standard prenatal care. These additions are designed to catch problems early and prepare for the safest possible delivery.

More Frequent Ultrasounds

Expect ultrasound evaluations approximately every 4–6 weeks (sometimes more often) to track:

• PAS progression and depth of placental invasion
• Fetal growth and development
• Cervical length (to watch for early shortening)
• Amniotic fluid levels

These frequent ultrasounds serve as your care team's primary window into how the pregnancy is progressing and whether the delivery plan needs adjustment.45

Anemia Screening and Iron Optimization

Because PAS deliveries carry a high risk of significant blood loss, optimizing your blood counts before delivery is critical. Your care team will monitor your complete blood count (CBC) more frequently than in a standard pregnancy:

• Second trimester: CBC checked monthly
• Third trimester: CBC checked every 2–4 weeks
• Target hemoglobin: greater than 11 g/dL (the oxygen-carrying protein in your red blood cells)

If your hemoglobin is low, treatment typically starts with oral iron supplements. If those are insufficient or not tolerated, your provider may recommend IV iron (intravenous iron infusion, such as ferric carboxymaltose), which works faster and more reliably. A 2025 study in BMC Pregnancy and Childbirth found that IV iron given at 34 weeks in PAS patients significantly reduced transfusion needs and operating room time.6

Antenatal Fetal Surveillance

Starting at approximately 30–32 weeks, your baby will be monitored more closely through:

• Non-stress tests (NST): A belt placed around your abdomen monitors the baby's heart rate patterns for 20–40 minutes. You may have these once or twice weekly.
• Biophysical profile (BPP): A combination of ultrasound assessment and NST that evaluates fetal breathing, movement, muscle tone, amniotic fluid, and heart rate reactivity.

As your due date approaches, these monitoring sessions may increase to twice weekly to ensure your baby is tolerating the pregnancy well.

Blood Bank Preparation

One of the most important behind-the-scenes preparations is ensuring the blood bank is ready for your delivery. This typically includes:

• Early blood typing and antibody screening
• Cross-matching (ensuring compatible blood is available)
• 6 or more units of packed red blood cells (PRBCs) set aside for your surgery
• A massive transfusion protocol (MTP) established — a pre-planned rapid response for providing large volumes of blood products quickly if needed
• A cell salvage device (cell saver) available in the operating room to collect and recycle your own blood during surgery

Antenatal Corticosteroids

Because PAS babies are typically delivered before full term, your provider will administer betamethasone — a corticosteroid that helps mature the baby's lungs. The standard course is:

• Two injections of 12 mg each, given intramuscularly (IM)
• Doses separated by 24 hours
• Timed so that delivery occurs 2–7 days after administration, when the medication is maximally effective

RhoGAM (If Rh-Negative)

If your blood type is Rh-negative, you will receive the standard RhoGAM injection at 28 weeks. However, with PAS, you will also need additional doses after every bleeding episode. After each bleed, your provider should order a Kleihauer-Betke test (a blood test that measures how much of the baby's blood has mixed with yours) to determine whether additional RhoGAM doses are needed and in what quantity.

Lifestyle Modifications

Living with a PAS diagnosis often means making adjustments to your daily routine. While the evidence for some restrictions is limited, most maternal-fetal medicine (MFM) specialists recommend a cautious approach.

Activity Restrictions

ACOG acknowledges that strict bedrest is of "unproven benefit" for most pregnancy complications.9 However, most MFM specialists recommend PAS patients:

• Avoid strenuous exercise, heavy lifting (generally nothing over 15–20 lbs), and high-impact activities
• Light walking is generally encouraged and safe
• Expect progressive restriction after 28–30 weeks, with activity levels decreasing as delivery approaches
• Immediate rest if any bleeding occurs — contact your care team right away

Your provider will give you individualized activity guidelines based on your specific situation, including the location and severity of your PAS.

Pelvic Rest

Travel Restrictions

As your pregnancy progresses, staying close to your planned delivery center becomes increasingly important:

• From the late second trimester onward, plan to stay within 1–2 hours of your delivery hospital
• Many clinicians advise stopping air travel by 28–32 weeks
• Have an emergency transport plan at all times — know how to get to your delivery hospital quickly, including alternative routes
• Carry your medical records and your care team's contact information with you whenever you leave home

Mental Health and Emotional Support

A PAS diagnosis carries significant emotional weight. Research shows that patients with PAS experience elevated levels of anxiety, depression, and post-traumatic stress. This is a normal response to an abnormal situation — not a sign of weakness.

Your care plan should include:

• Regular mental health screening (such as the PHQ-9 for depression and GAD-7 for anxiety)
• Access to a perinatal mental health specialist or counselor familiar with high-risk pregnancy
• Connection with peer support groups

Preparing for Delivery — The Checklist

As your delivery date approaches, there are many moving pieces that need to come together. Use this checklist as a starting point for discussions with your care team. Not all items may apply to your situation, but each one is worth asking about.

Bring this list to your prenatal appointments and check off each item as it is confirmed. Feeling prepared can help ease some of the anxiety that comes with a PAS delivery.2

Summary Table

The following table provides a quick-reference overview of how common prenatal tests and practices are affected by a PAS diagnosis.

Urinary Tract Infections (UTIs) & PAS

Why UTIs Matter More in PAS

No PAS-specific UTI management guideline exists — recommendations must be extrapolated from general obstetric UTI guidelines and urologic surgical principles.10 PAS pregnancies differ from normal pregnancies in important ways that elevate UTI risk and complicate management:

• Placenta percreta can invade the bladder wall (~1 in 10,000 births), creating a direct interface between placental tissue and the urinary tract17
• Hematuria from bladder involvement can mask or complicate UTI diagnosis
• Many PAS patients are hospitalized from 28–34 weeks, increasing nosocomial infection exposure
• Untreated UTIs can trigger preterm labor — especially dangerous in PAS where emergent delivery has significantly worse outcomes than planned delivery1
• Infection/sepsis occurs in ~6% of PAS patients; E. coli is the most common pathogen identified16

Prenatal UTI Screening & Treatment

All pregnant individuals should be screened for asymptomatic bacteriuria (ASB) with urine culture early in prenatal care.10 ASB is found in 2–10% of pregnancies; if untreated, up to 30% develop acute pyelonephritis.

Safe antibiotics:

• Cephalexin (first-line) — safe throughout pregnancy
• Amoxicillin — safe but high resistance rates limit empiric use

Trimester-restricted antibiotics:

• Nitrofurantoin — safe in the 2nd and 3rd trimesters but CONTRAINDICATED at term or near delivery. This is particularly important for PAS since delivery is typically planned at 34–36 weeks.
• TMP-SMX — avoid in the 1st trimester and near term

A test-of-cure urine culture should be obtained 1–2 weeks after treatment completion to confirm clearance.10

Preoperative UTI Screening

Urine culture is recommended 1–2 weeks before planned delivery (typically planned at 34–36 weeks). Any positive culture should be treated with culture-directed antibiotics before surgery.

• Performing cystotomy or partial cystectomy on a bacterially-colonized bladder significantly increases infection risk12
• Standard perioperative prophylaxis: cefazolin 2 g IV, 15–60 minutes before incision11
• For PAS surgeries lasting >3 hours or with estimated blood loss (EBL) >1500 mL: redose prophylactic antibiotic 3–4 hours after initial dose11

Catheter-Associated UTIs (CAUTI) After PAS Surgery

CAUTI risk increases approximately 3–7% per day of catheterization.15 Prevention strategies include:

• Maintain closed, sterile drainage system
• Daily assessment of catheter necessity
• Meticulous catheter care with regular perineal hygiene
• Do NOT treat asymptomatic catheter-associated bacteriuria unless symptomatic (IDSA guideline)15
• Do NOT use routine prophylactic antibiotics solely to prevent CAUTI — this promotes resistance15
• Surveillance urine cultures if signs of infection develop
• Cystogram before catheter removal at ~3 weeks post-repair
• Obtain urine culture at time of catheter removal

Bladder Involvement & UTI Risk

Bladder and ureteral injury are common in PAS surgery:

• Cystotomy (bladder injury) occurs in ~27% of PAS cases12
• Ureteral injury in ~4% of cases12
• UTI rate: 7.6% overall PAS patients, 13.7% in percreta (grade 3)16

How bladder invasion amplifies UTI risk:

• Trophoblastic invasion destroys normal bladder urothelium
• Blood in the bladder creates a bacterial growth medium
• Surgical repair creates biofilm sites
• Risk of bladder necrosis (especially after uterine artery embolization)
• Vesicovaginal fistula risk

References