Can a uti interfere with pregnancy test

Background: False-positive results for human chorionic gonadotropic (hCG) on point-of-care (POC) devices can occur for a variety of technical and biological reasons. It has been postulated that urinary tract infection can result in false-positive POC hCG assays, but the cause of this phenomenon remains elusive. Gram-positive bacteria have previously been reported to express an hCG-like molecule. We investigated whether urinary tract infection with Gram-positive bacteria can result in false-positive POC hCG.

Methods: We utilized remnant clinical urine specimens that had been submitted for culture as part of evaluation for urinary tract infection. Urine specimens with >100,000 colony-forming units per milliliter of Gram-positive bacteria (n = 95) were tested on ICON 20 POC hCG tests (Beckman Coulter). Specimens from adult patients that had been collected for clinical testing in the prior 48 hours were included in the study, and only 1 specimen per patient was included.

Results: Of 95 patients with Gram-positive urine specimens, 42 (44%) were female, and the median age was 62 years. The most common bacteria identified during clinical urine culture of these patients' specimens were coagulase-negative Staphylococcus species (36/95, 38%), Enterococcus species (34/95, 36%), and Streptococcus agalactiae (9/95, 9%). Five of 95 (5.3%) urine specimens were positive for POC hCG. Chart review revealed that 3 specimens were from pregnant women and 2 were from patients with cancer diagnoses.

Conclusions: Urine specimens from patients suspected to have urinary tract infection with Gram-positive organisms did not cause positive results on POC hCG test devices.

Keywords: Gram-positive bacteria; false-positive; hCG; urinary tract infection.

© American Association for Clinical Chemistry 2020. All rights reserved. For permissions, please email: [email protected].

Before talking about how a false positive can happen, it’s important to understand how a pregnancy test actually works.

When you become pregnant, your body starts going through a huge number of rapid changes to prepare for the pregnancy. Most of these changes are triggered by hormones that affect different parts of your body. Hormonal changes are also the reason many women experience symptoms during early pregnancy such as nausea, lightheadedness, cramping, and body aches.

A pregnancy test works by detecting these hormone levels in your urine - specifically, the hormone hCG, or human chorionic gonadotropin. This hormone is produced by your body when you are pregnant, from cells produced in the placenta. When a pregnancy test detects its presence in your urine, it almost always means you are pregnant.

However, it takes time for hCG levels to build up in your body. hCG levels roughly double in your bloodstream every three days, but they are too low to detect until about 12 days after conception. If you take a pregnancy test before this, you could still get a negative result, even if you are actually pregnant. These “false negatives” are very common in early pregnancy. Pregnancy Care Center of Grants Pass offers free, professional-grade pregnancy tests. Call us at (541) 479-6264 or visit our website to schedule an appointment if you are experiencing pregnancy symptoms but have received a negative pregnancy test result. For a list of possible pregnancy symptoms, visit our page on this topic here.

The Trouble with False Positives
 

While false negatives are very common, a false positive - where a pregnancy test tells you you’re pregnant when you aren’t - is extremely rare. That’s because there are very few circumstances when your body would produce hCG without being pregnant.

Chemical Pregnancy

The most common cause of false positives is when you experience a “chemical pregnancy.” This term is slightly misleading, as a chemical pregnancy is actually a pregnancy, but it ends in very early miscarriage. Most chemical pregnancies spontaneously miscarry by about the fifth week. This is late enough that pregnancy tests can detect hCG in your body but too early for an ultrasound or other procedure. Contact your healthcare provider if you think you have experienced a miscarriage.

Ectopic Pregnancy

You can also get a positive pregnancy test result from an ectopic pregnancy, which is a pregnancy that implants outside the uterus. Ectopic pregnancies are relatively rare, but they are also extremely dangerous for the mother. If an ectopic pregnancy isn’t caught early, it could cause your fallopian tubes to rupture, causing massive internal injuries. A doctor or clinic can diagnose an ectopic pregnancy through an ultrasound examination. Contact your healthcare provider or go to the emergency room if you think you may have an ectopic pregnancy.

Medical Conditions and Medications

There are also some medical conditions that can cause false pregnancy positives. These conditions can vary, but some of the more common ones include urinary tract infections, ovarian cysts, and kidney diseases. Additionally, you can get a false pregnancy positive after taking certain medications, including anxiety medications like Xanax or Valium, medications containing promethazine, and certain antipsychotic and anticonvulsant medications.

Mistakes When Taking the Test

Finally, the most common cause of a false positive is simply not following instructions when taking a pregnancy test. You should always check to make sure the pregnancy test you are using isn’t expired, and you should carefully time how long the test is in your urine stream to get an accurate result.

How to Get an Accurate Pregnancy Test
 

The best way to make sure you get an accurate pregnancy diagnosis is to visit a doctor, clinic, or pregnancy center. These places all have trained and helpful staff who can ensure you take the test correctly and get an accurate result. If you do get a positive test, you can also follow up with an ultrasound to ensure your pregnancy is healthy and viable.

At Pregnancy Care Center of Grants Pass, we offer free pregnancy testing and free limited OB ultrasound examinations to provide accurate pregnancy test results in a simple, safe and convenient way. We also offer free educational resources and information on parenting, adoption, and abortion, as well as our Pathways class, which helps prepare men and women for successfully navigating pregnancy and early parenthood. Call us today at (541) 479-6264 or visit our website to schedule an appointment at our center and get your questions answered.