|Year : 2019 | Volume
| Issue : 3 | Page : 675-680
Gastric ultrasound assessment of non-laboring third trimester pregnant women and non-pregnant women
Mofeed A Abdelmaboud1, Mostafa M Sabra1, Wafik E Aly2
1 Department of Anesthesia and Intensive Care, Al-Azhar Faculty of Medicine for Boys, Cairo, Egypt
2 Department of Radiodiagnosis, Al-Azhar Faculty of Medicine for Boys, Cairo, Egypt
|Date of Submission||05-Oct-2019|
|Date of Decision||05-Oct-2019|
|Date of Acceptance||17-Nov-2019|
|Date of Web Publication||10-Feb-2020|
Mofeed A Abdelmaboud
Assistant Professor of Anesthesia and Intensive Care Al-Azhar Faculty of Medicine for Boys, Cairo, Egypt; Department of Anesthesia and Intensive Care Al-Azhar Faculty of Medicine for Boys, El-Shiekh El-Shami street Squil Ausim Giza, Cairo, 12992
Source of Support: None, Conflict of Interest: None
Background Qualitative and quantitative gastric ultrasound (US) assessment is a non-invasive method used successfully in both surgical patients and healthy volunteers.
Aim The primary outcome was to evaluate gastric content by US after fasting in both pregnant and non-pregnant women and to determine if there was difference in the aspiration risk between them. The secondary outcome is to determine whether US can be used for rapid assessment of gastric volume and risk of aspiration.
Patients and methods Fasted 135 non-laboring third trimester pregnant women (group P) and 135 non-pregnant women (group NP) fulfilling inclusion criteria were recruited in this study. Qualitative gastric US assessment was done for each patients in both groups after following fasting guideline. Patients showing grade 0 in both groups were further subdivided into three subgroups to drink either 100, 200, or 400 ml of water, then a second quantitative US assessment of antral cross-sectional area (CSA) (cm2) was done 2 min after drinking the water.
Results Regarding qualitative Arzola’s antral grading, grade 0 was significantly predominant in group NP (64.4 vs 51.1%), whereas grade 2 and solid content were predominant in group P (16.6 vs 3.7% and 8.1 vs 1.5%, respectively), but grade 1 was comparable between the two groups. With respect to CSA (cm2), it was significantly larger in group P than group NP with all volumes of water taken. There was a linear relationship between CSA and volumes of water taken in both groups.
Conclusion First, fasted pregnant patients were at more risk of aspiration as it showed more significant number of patients with grade 2 and solid contents but with less significant number of patients with grade 0 as compared with non-pregnant patients. Second, there was a linear relationship between CSA (cm2) and gastric fluid volume, so US can be used to assess preoperative gastric volume and risk of aspiration.
Keywords: non-laboring, non-pregnant, third trimester pregnant, ultrasound
|How to cite this article:|
Abdelmaboud MA, Sabra MM, Aly WE. Gastric ultrasound assessment of non-laboring third trimester pregnant women and non-pregnant women. Sci J Al-Azhar Med Fac Girls 2019;3:675-80
|How to cite this URL:|
Abdelmaboud MA, Sabra MM, Aly WE. Gastric ultrasound assessment of non-laboring third trimester pregnant women and non-pregnant women. Sci J Al-Azhar Med Fac Girls [serial online] 2019 [cited 2020 Feb 29];3:675-80. Available from: http://www.sjamf.eg.net/text.asp?2019/3/3/675/278046
| Introduction|| |
In 1946, Mendelson reported for the first time that a pregnant woman died from pneumonia caused by aspiration of gastric contents during general anesthesia, so great attention was paid by anesthesiologists to develop fasting guidelines .
Pulmonary aspiration of gastric contents is one of the most serious complications of obstetric anesthesia. Pregnant women are at great risk for this complication related to increased gastric volume owing to delayed gastric emptying during labor, increased intragastric pressure as the gravid uterus favors gastroesophageal regurgitations, together with high risk of difficult intubation during general anesthesia . So, the quantification of the gastric contents and volume may be of particular interest to anesthetists in case of emergency anesthesia in a laboring woman .
However, the gravid uterus introduces variations in the ultrasound (US) examination, as the stomach tends to be displaced cephalad and to the right when compared with nonpregnant subjects, which could affect volume estimation .
Bedsides, US is a valuable application for the assessment of gastric content and volume, which may change perioperative management .
Gastric US qualitative assessment allows accurate differentiation between an empty stomach and one containing clear fluids or solid/thick fluid contents .
Additionally, when clear fluid are present, US quantitative assessment can estimate gastric volume based on the cross-sectional area (CSA) of gastric antrum and can discriminates small volumes (≤1.5 ml/kg), consistent with baseline gastric secretions, from higher volumes that may increase risk of aspiration .
Although there is no strict ‘threshold volume’ above which there is increased risk of aspiration, gastric fluid volumes up to 1.5 ml/kg (around 100 ml for average adult) are common in fasting patients and are considered safe .
| Aim|| |
The primary outcome was to evaluate gastric content after fasting in both pregnant and nonpregnant women and to determine if there was difference in the aspiration risk between them. The secondary outcome was to determine whether US can be used for rapid assessment of gastric volume and risk of aspiration.
Sample size justification
Med Cal program version 220.127.116.11 ‘Oostende’ (Belgium City) was used for calculating sample size. The statistical calculator is based on 95% confidence interval and 80% power of study, with α error of 5%, and according to a previous study by Chen et al. , so it can be relied on in this study, and according to this value, minimal produced sample size of 255 cases was enough to find such a difference. Assuming 5% dropout, the sample size would be 270 cases, which were subdivided into two equal groups.
| Patients and methodsmethod|| |
After approval from Al-Azhar Anesthesia and Intensive Care Department in Cairo and Local Ethical Committee, and signed informed written consent from each patient, this study was done at Al-Hussein University Hospital in the period from August 2018 to March 2019.
Inclusion criteria included nonlaboring pregnant women with single fetus (gestational age ≥36 weeks), aged greater than or equal to 21 years, American Society of Anesthesiologist physical status I–II, and able to understand the idea of the study.
Exclusion criteria included gestational age less than 36 weeks, age less than 21 years, obesity (defined by BMI ≥35 kg/m2), multiple pregnancies, polyhydramnios, preeclampsia, gestational diabetes, patient refusal, previous history of gastric or esophageal surgery, and patients with history of gastroesophageal reflux or hiatus hernia.
All patients followed fasting guidelines (2 h for clear fluids, 6 h for a light meal, and 8 h for a fried or fatty meal). Preoperative antacid as aspiration prophylaxis was not routinely used.
A total of 135 non-labouring third trimester pregnant (group P) and 135 non-pregnant (group NP) patients fulfilling inclusion criteria were recruited in this study.
All scanning was done by a single operator with previous experience in the technique (>50 gastric US). The examination was done by Aloka machine (Aloka Europe Technical Centre, Carl Zeiss, Germay) using a curvilinear low-frequency transducer (3–5 MHz).
At first, qualitative US examination of gastric contents was performed after fasting in both groups.
The gastric contents was scored by using modification of the qualitative grading scale described by Arzola et al. , where grade 0 represents no gastric contents in both supine and the right lateral decubitus (RLD), grade 1 represents gastric contents was observed in RLD but not in supine decubitus, and grade 2 represents gastric content was observed in both supine and RLD.
The patients who showed Arzola’s grade 0 in both groups were further subdivided using computer randomization into three equal subgroups to drink either 100, 200, or 400 ml of water. The antral CSA (cm2) was scanned by US 2 0min after ingestion of water in the RLD, with head elevated 45°.
The group randomization numbers were concealed in sealed opaque envelopes that were opened after patient enrolment ([Table 1]).
SPSS version 17 program (SPSS Inc., Chicago, Illinois, USA), was used to enter data and statistical analysis. Data were presented as mean±SD, number, and percentage. Unpaired Student t-test was used for parametric data. χ2-Test was used for data collected as number (percentage). P value less than 0.05 was considered as statistically significant.
| Results|| |
The two groups were comparable regarding patient characteristics ([Table 2]).
Regarding Arzola’s antral grading, grade 0 was significantly predominant in group NP, whereas grade 2 and solid content were predominant in group P, but grade 1 was comparable between the two groups ([Table 3]).
The patients who showed Arzola’s grade 0 in both groups were further subdivided into three equal subgroups (23 patients in group P and 29 patients in group NP) to drink either 100, 200, or 400 ml of water. The antral CSA (cm2) was scanned by US 2 min after ingestion of water.
With respect to CSA (cm2), it was significantly larger in group P than group NP with all volumes of water taken ([Table 4]). There was a linear relationship between CSA and volumes of water taken in both groups ([Figure 1],[Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6]).
|Table 4 Cross-sectional area (cm2) for different volumes of water ingested|
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|Figure 1 The cross-sectional area of gastric antrum shown by ultrasound after following fasting guidelines in a third trimester pregnant woman.|
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|Figure 2 The cross-sectional area of gastric antrum shown by ultrasound after drinking 100 ml of water in a third trimester pregnant woman. GA, gastric antrum, IVC, inferior vena cava.|
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|Figure 3 The cross-sectional area of gastric antrum shown by ultrasound after drinking 200 ml of water in a third trimester pregnant woman. GA, gastric antrum; IVC, inferior vena cava.|
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|Figure 4 The cross-sectional area of gastric antrum shown by ultrasound after drinking 400 ml of water in a third trimester pregnant woman. GA, gastric antrum; IVC, inferior vena cava.|
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|Figure 5 Clinical algorithm for gastric point of care ultrasound and aspiration risk . Modified from http://www.gastricultrasound.org with permission.|
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|Figure 6 Cross-sectional area (cm2) for different ingested water volumes.|
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| Discussion|| |
The current study showed that Arzola’s antral grade 0 were significantly predominant in non-pregnant group (64.4 vs 51.1%), whereas grade 2 and solid content were predominant in pregnant group (15.6 vs 3.7% and 8.1 vs 1.5%, respectively), but grade 1 was comparable between the two groups (25.2% vs 30.4%). Jay et al.  found that, grades 0, 1, 2, and 3 were observed in 45.2%, 21.9%, 15.1%, 17.8% of parturient women, respectively. Putte et al.  observed that grades 0, 1, and 2 were shown in 66%, 28.3%, and 5.7% of patients, respectively, in pregnant groups and 66.7%, 21%, 12.3% of patients, respectively, in non-pregnant groups. Hakak et al.  showed that grades 0, 1, and 2 were shown in 13%, 78%, and 9% of pregnant women, respectively, but no women had solid volume. Our data differ from the work of Arzola et al.  who identified only one pregnant woman with a grade 2 antrum in their study of 103 term pregnant women. Perlas et al.  observed that antral grade 0 correspond to 0 ml gastric fluid volume, grade 1 correspond to volume less than 100 ml of 77% of patients, and grade 2 associated with volume more than 100 ml in 75% of participants. Arzola et al.  predicted gastric fluid volume in non-laboring pregnant women (0.4 ml/kg in grade 0, 1 ml/kg in grade 1, and 2.7 ml/kg in grade 2). Rouget et al.  found that grades 0, 1, and 3 were observed in 74%, 14%, and 12% of patients, respectively, in the pregnant group.
With respect to CSA (cm2) in the current study, it was significantly higher in pregnant group than non-pregnant group with all volume of water taken. There was a linear relationship between CSA and volume of water taken. Chen et al.  found that antral CSA increased according to intragastric fluid volume within the range of studied volumes, and the measured CSA by ultrasonography is linearly dependent on gastric volume, and they constructed formula based on demographic variables and the measured CSA for the prediction of volume values in pregnant women. The equation is volume (ml)=270.76+13.68×CSA−1.20×gestational age. Arzola et al.  observed improved linear relationship between the logarithm of CSA and ingested volume and developed a new formula for prediction of gastric volume based on CSA. The equation is volume (ml)=−327+ 215.2×log (CSA) (cm2). Hakak et al.  used the following formula in pregnant women to calculate the gastric volume in ml/kg: volume (ml/kg)=27.0+(14.6×right lateral CSA)−(1.28×age).
| Conclusion|| |
First, fasted pregnant patients were at more risk of aspiration, showing more significant number of patients with grade 2 and solid contents but with less significant number of patients with grade 0 compared with non-pregnant patients. Second, there was a linear relationship between CSA (cm2) and gastric fluid volumes, so US can be used to assess preoperative gastric volume and risk of aspiration.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Mendelson CL. The aspiration of stomach contents into the lungs during obstetric anesthesia. Am J Obstet Gynecol
Kinsella SM, Winton AL, Mushambi MC, Ramaswamy K, Swales H, Quinn AC et al.
Failed tracheal intubation during obstetric general anesthesia: a literature review. Int J Obstet Anesth
Wright PM, Allen RW, Moore J, Donnelly JP. Gastric emptying during lumbar extradural analgesia in labour: effect of fentanyl supplementation. Br J Anesth
Rouget C, Chassard D, Bonnard C, Pop M, Desgranges FP, Bouvet L. Changes in qualitative and quantitative ultrasound assessment of the gastric antrum before and after elective cesarean section in term pregnant women: a prospective cohort study. Anesthesia
Alakkad H, Kruisselbrink R, Chin KJ, Niazi AU, Abbas S, Chan VWS et al.
Point-of-care ultrasound defines gastric content and changes the anesthetic management of elective surgical patients who have not followed fasting instructions: a prospective case series. Canadian J Anesth
El-Boghdadly K, Kruisselbrink R, Chan VWS, Perlas A. Images in anesthesiology: gastric ultrasound. Anesthesiology
Lobo DN, Hendry PO, Rodrigues G, Marciani L, Totman JJ, Wright JW et al.
Gastric emptying of three liquid oral preoperative metabolic preconditioning regimens measured by magnetic resonance imaging in healthy adult volunteers: a randomised double-blind, crossover study. Clin Nutr
Bisinotto FM, Pansani PL, Silveira LA, Naves AA, Peixoto AC, Lima HM et al.
Qualitative and quantitative ultrasound assessment of gastric content. Rev Assoc Med Bras
Chen X, Chen F, Zhao Q, Zhangc L, Liu Z. Ultrasonographic measurement of antral area for estimating gastric fluid volume in pregnant women. J Clin Anesth
Arzola C, Perlas A, Siddiqui NT, Carvalho JC. Bedside gastric ultrasonography in term pregnant women before elective cesarean delivery: a prospective cohort study. Anesth Analg
Putte VDP, Vernieuwe L, Perlas A. Term pregnant patients have similar gastric volume to non-pregnant females: a single-centre cohort study. Br J Anesth
Perlas A, Davis L, Khan M, Mitsakakis N, Chan VW. Gastric sonography in the fasted surgical patient: a prospective descriptive study. Anesth Analg
Jay L, Zieleskiewicz L, ois-Pierrick FD, Cogniat BR, Pop M, Boucher P et al.
Determination of a cut-off value of antral area measured in the supine position for the fast diagnosis of an empty stomach in the parturient. A prospective cohort study. Eur J Anesthesiol
Hakak S, McCaul CL, Crowley L. Ultrasonographic evaluation of gastric contents in term pregnant women fasted for six hours. Int J Obstet Anesth
Arzola C, Perlas A, Siddiqui NT, Downey K, Ye XY, Carvalho JCA. Gastric ultrasound in the third trimester of pregnancy: a randomised controlled trial to develop a predictive model of volume assessment. Anesthesia
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]