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Phamn

Published: July 31, 2026Updated: August 16, 2026

This test measures the acidity or alkalinity of amniotic fluid to assess fetal well-being during pregnancy.

Quick summary

{"The test measures pH level of amniotic fluid surrounding the fetus","Normal amniotic fluid pH is between 7.0-7.5 (slightly alkaline)","Abnormal pH may indicate fetal distress or infection","Sample is collected via amniocentesis or during labor","Results help doctors make decisions about pregnancy management"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
2743-3
Short code
pH Amn
Synonyms
pH Amn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
not specified
Ref low
7
Ref high
7.5
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

The amniotic fluid pH test measures how acidic or alkaline (basic) the amniotic fluid is. Amniotic fluid is the protective liquid that surrounds the unborn baby (fetus) in the uterus. This test is performed using a sample of amniotic fluid, not serum, collected through amniocentesis or during labor.

Why is it important?

The pH level of amniotic fluid can indicate the health status of the fetus. A normal pH (7.0-7.5) suggests the baby is doing well. Abnormal pH levels may signal problems such as fetal hypoxia (lack of oxygen), infection, or other complications that require medical attention.

How is the test performed?

A healthcare provider collects a small sample of amniotic fluid using a thin needle guided by ultrasound (amniocentesis), or the fluid may be collected during labor if the amniotic sac has ruptured. The sample is then tested in a laboratory to determine its pH level.

What do the results mean?

Normal amniotic fluid pH ranges from 7.0 to 7.5. A pH below 7.0 (acidic) may suggest fetal distress, oxygen deprivation, or infection. A pH above 7.5 (alkaline) is less common but may also indicate complications. Your healthcare provider will interpret the results in context with other clinical findings.

Reference range

7.0-7.5not specified

Specimen: serum

Sample obtained via amniocentesis; no fasting required

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Is the amniotic fluid pH test painful?
Amniocentesis, used to collect amniotic fluid, may cause brief discomfort or cramping. Local anesthesia is often used to minimize pain. The procedure is generally well-tolerated.
Are there any risks to this test?
Amniocentesis carries a small risk of complications, including infection, bleeding, leakage of amniotic fluid, or miscarriage. The risk is low (less than 1%) when performed by experienced healthcare providers.
How long does it take to get results?
Results are typically available within a few hours to a day, depending on the laboratory. The pH test itself is relatively quick.
Do I need to fast before this test?
No fasting is required for this test. You can eat and drink normally before the procedure.
What happens if my results are abnormal?
If amniotic fluid pH is abnormal, your healthcare provider will discuss further evaluation and treatment options. This may include additional testing, monitoring, or delivery planning depending on the severity and cause of the abnormal result.
  1. 1
    MedlinePlus - Amniotic fluidSource
  2. 2
    American College of Obstetricians and Gynecologists (ACOG)Source
  3. 3
    Mayo Clinic - AmniocentesisSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy